Commonly Confused Suffixes: -tion vs. -sion  

Spelling rules for words that end in “-tion” or “-sion”

The suffixes “-tion” and “-sion” are both used to create nouns from verbs (and, less commonly, adjectives and other nouns) to describe a state, condition, action, process, practice, or the result thereof. They are actually just permutations of the same suffix, “-ion,” but there are specific conditions that will dictate which one we use, so it’s worthwhile to consider them individually.
(There is also a third version, “-cion,” but this only occurs in two specific instances: coercion, from the verb coerce, and suspicion, from the verb suspect.)

When to use “-tion”

The “-tion” ending is so ubiquitous because it is the more straightforward of the two to form. In most cases, “-ion” simply attaches to words ending in “-t” or “-te” (in which case it replaces the silent final E), so “-tion” is just the natural product of forming the noun. (Unlike “-sion,” which more often alters the basic spelling of a word.)
With that in mind, there are some specific verb endings that can take the “-ion” suffix. In some cases, the resulting suffixed ending forms the basis for a spelling pattern that can be applied to other verbs.

Rule 1: Use “-tion” with verbs ending in “-ate”

A verb that ends in “-ate” will very often be able to become a noun using the “-ion” suffix. When this is the case, “-ion” replaces the silent E of the base word.
For example:
  • abbreviate→abbreviation
  • accommodate→accommodation
  • celebrate→celebration
  • communicate→communication
  • cooperate→cooperation
  • dedicate→dedication
  • depreciate→depreciation
  • educate→education
  • exhilarate→exhilaration
  • fluctuate→fluctuation
  • formulate→formulation
  • generate→generation
  • hallucinate→hallucination
  • hesitate→hesitation
  • illuminate→illumination
  • impersonate→impersonation
  • innovate→innovation
  • legislate→legislation
  • liberate→liberation
  • manipulate→manipulation
  • migrate→migration
  • negotiate→negotiation
  • notate→notation
  • obliterate→obliteration
  • operate→operation
  • perpetuate→perpetuation
  • populate→population
  • radiate→radiation
  • rotate→rotation
  • separate→separation
  • speculate→speculation
  • terminate→termination
  • translate→translation
It’s worth noting that, based on this pattern, “-ation” can function like a separate suffix of its own, attaching to other verbs not ending in “-ate.” For instance:
  • allege→allegation
  • alter→alteration
  • cancel→cancellation
  • cause→causation
  • compile→compilation
  • declare→declaration
  • exalt→exaltation
  • flirt→flirtation
  • float→flotation
  • inhale→inhalation
  • prepare→preparation
  • strangle→strangulation
  • starve→starvation
The use of “-ation” with verbs such as these is rather difficult to predict, because it occurs with so many different and varied endings; for the most part, we just have to memorize them. However, there are certain verb endings that do predictably take the “-ation” suffix at the end.

Rule 1.1 Use “-ation” with verbs ending in “-ize”

This is by far the most common verb ending to take the “-ation” suffix, which replaces the silent E at the end of the word. Though there are far too many words to include an exhaustive list here, let’s look at some common examples:
  • alphabetize→alphabetization
  • authorize→authorization
  • characterize→characterization
  • customize→customization
  • democratize→democratization
  • dramatize→dramatization
  • equalize→equalization
  • fictionalize→fictionalization
  • generalize→generalization
  • globalize→globalization
  • immunize→immunization
  • italicize→italicization
  • hospitalize→hospitalization
  • liberalize→liberalization
  • memorize→memorization
  • mobilize→mobilization
  • normalize→normalization
  • optimize→optimization
  • organize→organization
  • personalize→personalization
  • realize→realization
  • romanticize→romanticization
  • specialize→specialization
  • stylize→stylization
  • utilize→utilization
  • verbalize→verbalization
  • visualize→visualization

Rule 1.2: Use “-ation” with verbs ending in “-ify”

The second most common verbs to take the “-ation” suffix are those ending in “-ify.” However, instead of simply adding the suffix to the end of the word, we must make some changes to its overall spelling. First, Y changes I, then we add the letter C and then add “-ation.” For example:
  • amplify→amplification
  • beautify→beautification
  • certify→certification
  • clarify→clarification
  • classify→classification
  • deify→deification
  • edify→edification
  • electrify→electrification
  • falsify→falsification
  • fortify→fortification
  • gentrify→gentrification
  • glorify→glorification
  • humidify→humidification
  • intensify→intensification
  • justify→justification
  • magnify→magnification
  • mystify→mystification
  • notify→notification
  • objectify→objectification
  • personify→personification
  • ramify→ramification
  • simplify→simplification
  • specify→specification
Note that there are several verbs that end “-efy,” and while this ending sounds the same as “-ify,” such verbs take a different form when the “-tion” suffix is attached:
  • liquefy→liquefaction
  • putrefy→putrefaction
  • rarefy→rarefaction
  • stupefy→stupefaction
  • tumefy→tumefaction

Rule 1.3: Use “-ation” with verbs ending in “-aim”

Not many verbs end in “-aim,” but those that do can usually take the “-ation” suffix to become nouns (though only if the word has more than one syllable). Note that, when this happens, the letter I is omitted from “-aim.” For example:
  • acclaim→acclamation
  • declaim→declamation
  • disclaim→disclamation
  • exclaim→exclamation
  • proclaim→proclamation
  • reclaim→reclamation

Rule 2: Use “-tion” with verbs ending in “-pt”

Verbs ending in “-pt” will simply take “-ion” to form nouns; they never use “-sion.” For example:
  • adopt→adoption
  • corrupt→corruption
  • encrypt→encryption
  • except→exception
  • erupt→eruption
  • exempt→exemption
  • intercept→interception
  • interrupt→interruption
(There are two exceptions to this: the verbs adapt and tempt take the “-ation” suffix rather than simply adding “-ion” to the end, becoming adaptation and temptation.)
In certain cases, though, a verb’s ending will change to “-ption” to become a noun. Again, it is always “-tion” that is used with these verbs; we never have a word ending in “-psion.”

Rule 2.1: Use “-ption” with verbs ending in “-scribe”

Verbs ending in the root “-scribe” will take the “-tion” suffix to become nouns. However, we omit the silent E and change B to P, as in:
  • ascribe→ascription
  • conscribe→conscription
  • describe→description
  • inscribe→inscription
  • prescribe→prescription
  • proscribe→proscription
  • subscribe→subscription
  • transcribe→transcription

Rule 2.2: Use “-ption” with verbs ending in “-ceive”

Verbs ending in the root “-ceive” will also take the “-ption” ending. Like verbs ending in “-scribe,” we have to make some changes to the overall spelling of the word when adding the suffix. In this instance, “-ive” is omitted and replaced by “-ption,” as in:
  • conceive→conception
  • deceive→deception
  • perceive→perception
  • receive→reception

Rule 2.3: Use “-ption” with verbs ending in “-sume”

Finally, we also use “-ption” with verbs ending in “-sume.” This time, though, we merely omit silent E and add “-ption” to the end:
  • assume→assumption
  • consume→consumption
  • presume→presumption
  • resume→resumption
  • subsume→subsumption

Rule 3: Use “-tion” with words ending in “-ct”

Like words ending in “-pt,” most verbs and adjectives ending in “-ct” will simply take “-ion” to form nouns of quality or status. Other nouns simply end in “-ction” without being derived from a verb or adjective. Just remember that when the (/-ʃən/) sound follows a C, it will always be spelled “-ction.”
Quite a few words will take this ending, so let’s just look at some common examples:
  • abstract→abstraction
  • act→action
  • attract→attraction
  • auction
  • benefaction
  • connect→connection
  • correct→correction
  • deduct→deduction*
  • distinct→distinction
  • distract→distraction
  • elect→election
  • extinct→extinction
  • fraction
  • function
  • instruct→instruction
  • intersect→intersection
  • junction
  • object→objection
  • obstruct→obstruction
  • perfect→perfection
  • protect→protection
  • react→reaction
  • reflect→reflection
  • subtract→subtraction
  • traction
  • transact→transaction
*The noun deduction is also associated with a different, unrelated verb: deduce. In fact, most verbs that end in “-duce” will take the “-tion” suffix in the same way, as in:
  • deduce→deduction
  • induce→induction
  • introduce→introduction
  • produce→production
  • reduce→reduction
  • seduce→seduction
  • transduce→transduction
Finally, this “-ction” spelling pattern is applied to another verb that is completely different from what we’ve seen so far: suck→suction.

Rule 4: Use “-tion” with verbs ending in “-ete”

If a verb (or, less commonly, an adjective) ends in “-ete,” then it will take the “-ion” suffix by omitting the silent E at the end.
  • complete→completion
  • concrete→concretion
  • delete→deletion
  • deplete→depletion
  • excrete→excretion
  • replete→repletion
  • secrete→secretion
Uniquely, the verb compete does not become competion, but competition. (Also following this pattern, the verb repeat becomes repetition.)
discrete vs. discreet (vs. discretion)
The noun discretion is very similar in structure to the other words we looked at in Rule 4, and, based on that pattern, we would expect it to be derived from the adjective discrete, meaning “distinct, unconnected, or separate in function or form.” Discretion, however, is actually the noun form of the adjective discreet, meaning “careful to avoid social awkwardness or discomfort, especially by not sharing delicate information.”
Because discrete and discreet are both pronounced the same way (/dɪˈskrit/), and the noun discretion looks like it ought to be derived from discrete (the noun form of discrete is discreteness), it’s easy to get these two terms confused. Here’s a helpful mnemonic to help remember the appropriate meaning for the two different spellings:
  • Discrete means “separate” or “distinct,” so we must separate the last two Es with a T.

Rule 5: Use “-tion” with verbs ending in “-ute”

Like verbs ending “-ete,” we can simply attach “-ion” to verbs ending in “-ute” by omitting the silent E, as in:
  • attribute→attribution
  • contribute→contribution
  • dilute→dilution
  • distribute→distribution
  • execute→execution
  • institute→institution
  • pollute→pollution
  • persecute→persecution
  • substitute→substitution

Rule 5.1: Use “-ution” for verbs ending in “-olve”

Like “-ation” and “-ption,” the “-ution” ending can also function as a separate suffix in certain circumstances. Here, it is applied to verbs ending in “-olve,” taking the place of the letters V and E. For instance:
  • absolve→absolution
  • evolve→evolution
  • involve→involution
  • resolve→resolution
  • revolve→revolution
  • solve→solution

Rule 6: Use “-tion” with words ending in “-it” or “-ite”

  • contrite→contrition
  • edit→edition
  • erudite→erudition
  • exhibit→exhibition
  • expedite→expedition
  • extradite→extradition
  • fruit*→fruition
  • ignite→ignition
  • inhibit→inhibition
  • intuit→intuition
  • prohibit→prohibition
  • transit→transition
(*Meaning “to produce fruit”; the noun fruition is more usually used figuratively.)
Note, however, that verbs ending in “-mit” do not take the “-tion” ending, but rather “-mission,” which we’ll look at a little bit further on.

Rule 6.1: Use “-ition” with verbs ending in “-ose”

The “-ition” ending is also commonly used with verbs ending in “-ose.” With these words, it replaces the silent E at the end:
  • appose→apposition
  • compose→composition
  • decompose→decomposition
  • depose→deposition
  • dispose→disposition
  • juxtapose→juxtaposition
  • impose→imposition
  • oppose→opposition
  • propose→proposition
  • suppose→supposition
  • transpose→transposition

When to use “-sion”

Rule 1: Use “-sion” when it is pronounced /-ʒən/

One of the distinguishing features of the “-sion” ending compared to “-tion” is the fact that it most often forms the /-ʒən/ sound, as heard in the word vision (/ˈvɪʒən/). This can easily be considered a rule unto itself, because “-tion” never makes the /-ʒən/ sound; it is always pronounced /-ʃən/, as in portion (/ˈpɔrʃən/).
That being said, there are still specific spelling patterns that dictate when (and, in some cases, how) a word can take the “-sion” ending, so it’s important to look at the different spelling conventions associated with this suffix.

Rule 2: Use “-sion” with verbs ending in “-de”

One of the most reliable spelling indicators of when a verb will take “-sion” rather than “-tion” is when it ends in “-de.” This is most commonly seen in words ending in “-ade” and (even more so) “-ude,” but it also occurs in “-ide” and “-ode” words as well. Regardless of the vowel that precedes it, “-de” is always omitted and replaced by “-sion.”
For example:
Verbs ending in “-ade”
Verbs ending in “-ide”
Verbs ending in “-ode”
Verbs ending in “-ude”
abrade→abrasion
corrode→corrosion
dissuade→dissuasion
evade→evasion
invade→invasion
persuade→persuasion
pervade→pervasion
collide→collision
decide→decision
elide→elision
provide→provision
corrode→corrosion
erode→erosion
explode→explosion
implode→implosion
allude→allusion
collude→collusion
conclude→conclusion
delude→delusion
elude→elusion
exclude→exclusion
extrude→extrusion
include→inclusion
intrude→intrusion
obtrude→obtrusion
occlude→occlusion
preclude→preclusion
protrude→protrusion
seclude→seclusion
We also use the “-sion” suffix with verbs ending in “-cede,” but the resultant nouns are both spelled and pronounced differently, so we’ll look those examples separately further on.

Rule 3: Use “-sion” with verbs ending in “-ise” and “-use”

The “-sion” suffix is also used when a verb ends in “-ise” or, more commonly, “-use.” However, unlike with words ending in “-de,” this is because only silent E is omitted when it takes the suffix “-ion” rather than the word’s spelling being changed to “-sion.”
For example:
Verbs ending in “-ise”
Verbs ending in “-use”
incise→incision
revise→revision
supervise→supervision
confuse→confusion
contuse→contusion
diffuse→diffusion
effuse→effusion
infuse→infusion
fuse→fusion
suffuse→suffusion
transfuse→transfusion
It’s also worth noting that there are two adjectives ending in “-ise” that can take the “-sion” ending to become nouns: concise→concision and precise→precision. Likewise, two non-verbs ending in “-use” follow this pattern as well: the adjective profuse becomes profusion, and the noun recluse becomes reclusion.

Rule 4: Use “-sion” with verbs ending in “-pel”

Another instance in which we use the “-sion” ending instead of “-tion” is for verbs ending in “-pel.” Again, the spelling of the word changes slightly to accommodate the suffix, this time changing from “-pel” to “-pul-,” followed by “-sion.”
  • compel→compulsion
  • expel→expulsion
  • impel→impulsion
  • propel→propulsion
  • repel→repulsion
Though not ending in “-el,” the verb convulse also has a noun that has this form: convulsion. There are a few other words that follow this spelling pattern, too, but they are not derived from existing base verbs:
  • avulsion
  • emulsion
  • evulsion
  • revulsion

When “-sion” is pronounced /-ʃən/

The suffix “-sion” is most often pronounced /-ʒən/, but there are some instances in which it is pronounced /-ʃən/, the same as “-tion.”
The most common spelling associated with this pronunciation is “-ssion,” and there are a few conventions determining when this spelling will occur. (It can also be pronounced this way after the letter N, but we’ll look at that separately further on.)

Rule 5: Use “-sion” with verbs ending in “-mit”

As we mentioned in Rule 6 above, the “-tion” suffix is used with words ending in “-it” except for verbs specifically ending in “-mit.” For words with this ending, the “-ion” suffix changes the final T to SS.
For example:
  • admit→admission
  • commit→commission
  • emit→emission
  • omit→omission
  • permit→permission
  • remit→remission
  • submit→submission
  • transmit→transmission

Rule 6: Use “-sion” with verbs ending in “-cede”

Another verb ending that follows this pattern is “-cede.” Similar to “-mit,” we replace “-de” with “-ssion.” Note as well that this suffix also changes the pronunciation of the vowel E from /i/ in “-cede” (/sid/) to /ɛ/ in “-cession” (/sɛʃən/).
For example:
  • accede→accession
  • concede→concession
  • intercede→intercession
  • precede→precession
  • recede→recession
  • secede→secession
This pattern is also used for the very similarly spelled verbs proceed (procession) and succeed (succession).

Rule 7: Use “-sion” with verbs ending in “-ss”

Finally, many verbs that naturally end in a double S will simply take “-ion” on the end with no other change to the words’ spelling. For example:
  • aggress→aggression
  • compress→compression
  • concuss→concussion
  • confess→confession
  • depress→depression
  • digress→digression
  • discuss→discussion
  • egress→egression
  • express→expression
  • impress→impression
  • obsess→obsession
  • oppress→oppression
  • percuss→percussion
  • possess→possession
  • profess→profession
  • regress→regression
  • suppress→suppression
  • transgress→transgression

“-tion” vs. “-sion” after N and R

Many spelling guides indicate that “-sion” very often occurs after the consonants N and R. While this is true, “-tion” also commonly occurs after these consonants, so we cannot use N or R on their own to decide whether a word’s ending will be “-tion” or “-sion.”
Thankfully, there are a few other spelling patterns that can help us determine the correct ending to use.

After N

Because “-ntion” and “-nsion” are both pronounced the same way (/-nʃən/), we must rely on the spelling of the verb to which the suffix attaches in order to decide which one is correct.

When to use “-tion”

When verbs end in “-tain,” “-vene,” or “-vent,” we use the “-tion” suffix. (Note that “-tain” becomes “-tention,” and “-vene” becomes “-vention.”) For instance:
  • abstain→abstention
  • circumvent→circumvention
  • contravene→contravention
  • convene→convention
  • detain→detention
  • invent→invention
  • prevent→prevention
  • retain→retention
Note that there is one verb ending in “-ent” that will take “-sion” rather than “-tion”: dissent→dissension (though it has an accepted variant spelling of dissention).

When to use “-sion”

While we use “-tion” after verbs ending in “-ent,” we use “-sion” after verbs ending in “-end,” as in:
  • apprehend→apprehension
  • ascend→ascension
  • comprehend→comprehension
  • descend→descension (more commonly descent)
  • distend→distension
  • extend→extension
  • reprehend→reprehension
  • suspend→suspension
However, there are two notable exceptions to the “-end” rule: the verb intend becomes the noun intention, and the verb contend becomes contention. (The noun attention is also etymologically related to the verb attend, but the two are not directly related in modern meaning. The noun of state, condition, action, process, or practice derived from attend is attendance.)
There are also a few specific verbs with endings other than those we’ve seen that can take “-sion” after N:
  • decline→declension
  • expand→expansion
Note that the noun pretense (or pretence in British English) and the adjective tense both take the “-sion” suffix as well: pretension and tension. The adjective intense can also become intension (which rhymes with intention but means “the state of being or the act of becoming intense”), but this is fairly uncommon compared to the synonym intensity.

After R

Focusing purely on pronunciation, a word will always take the “-sion” ending after R when it is pronounced /-rʒən/; “-rtion” is always pronounced /-rʃən/.
(Note, though, that “-rsion” can also be pronounced /-rʃən/ depending on the speaker’s dialect [especially in British English], so it’s still important consider the base word’s spelling when deciding which suffix to use.)

When to use “-tion”

Generally speaking, we use “-tion” with verbs ending in “-rt,” as in:
  • assert→assertion
  • contort→contortion
  • desert→desertion
  • distort→distortion
  • exert→exertion
  • extort→extortion
  • insert→insertion

When to use “-sion”

However, there is a major exception to the “-rt” rule: we use “-sion” with words ending in “-vert,” with the final T being replaced by the suffix. For example:
  • convert→conversion
  • divert→diversion
  • extrovert→extroversion
  • introvert→introversion
  • invert→inversion
  • revert→reversion
  • subvert→subversion
We also use the “-sion” ending after R with three other types of verb endings, too: “-erse,” “-ur,” and “-erge.” For instance:
  • asperse→aspersion
  • averse→aversion
  • disperse→dispersion
  • emerge→emersion (the synonym emergence is much more common)
  • excur→excursion (though the verb excur is now obsolete)
  • immerse→immersion
  • incur→incursion
  • recur→recursion
  • submerge→submersion (the verb submerse is also related, though it may be a back-formation from submersion)

When to use “-cion” and “-cian”

As we mentioned at the beginning of the section, there is actually a third variation of this suffix in addition to “-tion” and “-sion”: “-cion.” It is used to form the nouns coercion and suspicion.
A very similar suffix, “-cian” (also pronounced /-ʃən/), is used much more commonly than “-cion,” but it has a different function and meaning than “-tion,” “-sion,” and “-cion.” Rather than indicating a state, condition, action, process, or practice, “-ician” indicates a person who practices, performs, or specializes in a particular subject or activity. For example:
  • arithmetic→arithmetician
  • beauty→beautician
  • diet→dietician (also spelled dietitian)
  • electricity→electrician
  • magic→magician
  • mathematics→mathematician
  • music→musician
  • optics→optician
  • pediatrics→pediatrician
  • statistics→statistician
Quiz

1. Which of the following is the most common permutation of the “-ion” suffix?





2. Which of the following words takes the suffix “-tion”?





3. Which of the following words takes the suffix “-sion”?





4. True or False: The suffixes “-cian” and “-cion” have the same function and meaning.



5. True or False: The suffixes “-tion” and “-sion” can both be pronounced /-ʃən/.



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