Commonly Confused Suffixes: -er, -or, and -ar  

When to use “-er,” “-or,” or “-ar” at the end of a word

The suffixes “-er,” “-or,” and “-ar” are all used to create nouns of agency (indicating “a person or thing that performs an action”) from verbs. Of the three, “-er” is by far the most common, while “-or” is much more common than “-ar.” Because they perform the same function and are pronounced in the same way (/ər/), it can be difficult to decide which suffix is the correct one to use.
When a verb is changed into a noun of agency using a suffix, it will almost always be “-er.” However, there are a few particular conventions we can follow to determine when we should use “-or” instead. (We use the “-ar” suffix much more rarely, so we will discuss it separately toward the end of the section.)

Rule 1: Use “-er” with verbs ending in a single consonant

When a verb ends in a single consonant, it will almost always take the suffix “-er.” Note that if the consonant is preceded by a single vowel, the consonant will generally double before the suffix (though this is not always the case; go to the section Doubling Consonants with Vowel Suffixes to learn more).
For example:
  • bat→batter
  • barter→barterer
  • canvas→canvasser
  • cater→caterer
  • cheat→cheater
  • eat→eater
  • embroider→embroiderer
  • feel→feeler
  • fib→fibber
  • format→formatter
  • grab→grabber
  • loiter→loiterer
  • loot→looter
  • propel→propeller
  • rap→rapper
  • read→reader
  • scrub→scrubber
  • sit→sitter
  • shred→shredder
  • travel→traveler
  • yak→yakker
There are several exceptions to this rule, though:
  • conquer→conqueror
  • council→councilor
  • counsel→counselor
  • offer→offeror
  • sail→sailor

Rule 1.5: Use “-or” with multi-syllable verbs ending in “-it”

While single-syllable verbs that end in “-it” will usually take the suffix “-er” and have the final T doubled (as in hitter, knitter, quitter, sitter, etc.), verbs with two or more syllables ending in “-it” are much more likely to take the suffix “-or.” For example:
  • audit→auditor
  • credit→creditor
  • edit→editor
  • exhibit→exhibitor
  • inherit→inheritor
  • inhibit→inhibitor
  • solicit→solicitor
  • visit→visitor
While this convention is fairly reliable, there are some exceptions:
  • delimit→delimiter
  • profit→profiter
  • recruit→recruiter
Also note that this convention does not apply when a silent E follows the final T.

Rule 2: Use “-er” with verbs ending in a silent E

Most verbs that end in a consonant + silent E will take the “-er” suffix (which replaces the final E of the root word). For instance:
  • advertise→advertiser
  • bake→baker
  • bathe→bather
  • change→changer
  • code→coder
  • divide→divider
  • frame→framer
  • give→giver
  • grate→grater
  • hate→hater
  • love→lover
  • make→maker
  • organize→organizer
  • page→pager
  • ride→rider
  • slide→slider
  • time→timer
  • write→writer
This is a reliable convention to follow, but there are some exceptions, most often when a word ends in “-ise”:
  • incise→incisor
  • previse→previsor
  • promise→promisor (variant of promiser, used especially in legal writing)
  • supervise→supervisor
  • survive→survivor
However, the most consistent exception is for verbs with more than one syllable that end in “-ate.”

Rule 2.5: Use “-or” with multi-syllable verbs ending in “-ate”

When a word has more than one syllable and ends in “-ate,” it will almost always take the “-or” suffix. Once again, the suffix replaces the silent E at the end. For example:
  • accelerate→accelerator
  • administrate→administrator
  • animate→animator
  • calculate→calculator
  • coordinate→coordinator
  • educate→educator
  • elevate→elevator
  • generate→generator
  • instigate→instigator
  • liberate→liberator
  • motivate→motivator
  • narrate→narrator
  • perpetrate→perpetrator
  • refrigerate→refrigerator
  • spectate→spectator
  • terminate→terminator
  • ventilate→ventilator
Remember, single-syllable verbs ending in “-ate” will take the “-er” suffix, as in grater, hater, skater, etc.

Rule 3: Use “-er” with verbs ending in consonant clusters

So far we’ve mostly looked at examples of verbs that end in a single consonant and a silent E, with a few different instances in which “-or” is (or might) be used instead of “-er.”
However, when a verb ends in a consonant cluster (two or more consonants that quickly blend together in the same syllable), it is much more likely to take the “-er” suffix.
For example:
  • adapt→adapter*
  • bend→bender
  • boost→booster
  • build→builder
  • busk→busker
  • contend→contender
  • defend→defender
  • dust→duster
  • forest→forester
  • golf→golfer
  • grind→grinder
  • help→helper
  • jump→jumper
  • lend→lender
  • mend→mender
  • protest→protester
  • respond→responder
  • shoplift→shoplifter
  • tempt→tempter
  • weld→welder
However, there are a few common exceptions to this convention:
  • invent→inventor
  • invest→investor
  • sculpt→sculptor
  • torment→tormentor
  • vend→vendor
(*Adapter can also be spelled adaptor, but this is a bit less common.)
Uniquely, we more commonly use “-or” when a word ends in the cluster CT.

Rule 3.5: Use “-or” with verbs ending in CT

While verbs ending in other consonant clusters will take the “-er” suffix, a verb that ends in CT will almost always be made into a noun with the suffix “-or,” as in:
  • abduct→abductor
  • act→actor
  • conduct→conductor
  • contract→contractor
  • correct→corrector
  • direct→director
  • eject→ejector
  • instruct→instructor
  • object→objector
  • project→projector
  • react→reactor
  • reflect→reflector
  • select→selector

Rule 4: Use “-er” with verbs ending in consonant digraphs

Like we do with verbs ending in consonant clusters (other than CT), we use the “-er” suffix with verbs ending in consonant digraphs, pairs of consonants that form a single unique consonant sound. This is also true of words ending in the consonant trigraph TCH.
For example:
  • catch→catcher
  • choreograph→choreographer
  • cough→cougher
  • etch→etcher
  • laugh→laugher
  • march→marcher
  • publish→publisher
  • sing→singer
  • teach→teacher
  • wash→washer
  • watch→watcher
This is also true when a verb ends in a double consonant (except SS, as we’ll see later). For example:
  • bluff→bluffer
  • buzz→buzzer
  • call→caller
  • distill→distiller
  • mill→miller
  • roll→roller
  • spell→speller
  • staff→staffer

Rule 4.5: There’s no pattern for verbs ending in SS

While verbs ending in FF, LL, or ZZ will always take the suffix “-er,” there is much less certainty for words ending in SS—there is no clear pattern, so we just have to memorize which suffix a particular word will take.

Using the suffix “-ar”

While “-er” is the most common suffix to form nouns of agency from verbs, the suffix “-or” performs the same function in certain instances. However, there is a third suffix that can be used to form these types of nouns, and it is pronounced the same way as the other two: “-ar.”

Nouns of agency ending in “-ar”

Nouns of agency ending in the “-ar” suffix are much less common than “-er” or “-or,” and there is no real convention to dictate when “-ar” is the appropriate ending.
There are only two nouns that can be directly derived from verbs using “-ar”:
  • beg→beggar
  • lie→liar
There is a third verb that is connected to a noun of agency: burgleburglar. In this case, however, burglar is the original word (derived from Anglo-Latin) with the verb burgle derived from it, a process known as a “back-formation.”
Finally, there are a few other nouns of agency that end in “-ar,” but they are not derived from or directly connected to a verb, so “-ar” is not functioning as a suffix:
  • bursar
  • registrar
  • scholar
  • vicar

Other nouns ending in “-ar”

In addition to ending some nouns of agency, “-ar” appears at the ends of several other common nouns. However, it is not functioning as a suffix in these cases, as it does not change a different part of speech into a noun. For instance:
  • altar
  • avatar
  • calendar
  • cheddar
  • dollar
  • grammar
  • guitar
  • hangar (meaning “a large building or shelter, usually to house aircraft”; not related to the verb hang)
  • mortar
  • nectar
  • pillar
  • radar
  • vinegar

Using “-ar” to form adjectives

While the suffix “-ar” is used to form a few nouns, it is much more commonly used to create adjectives, either on its own or as part of the larger suffix “-ular.” (Both “-ar” and “-ular” are used to mean “like; resembling or relating to; of or belonging to.”)
For example:
  • angle→angular
  • cell→cellular
  • circle→circular
  • grain→granular
  • line→linear
  • muscle→muscular
  • nucleus→nuclear
  • pole→polar
  • populace→popular
  • title→titular
  • vehicle→vehicular

Forming Comparative Adjectives and Comparative Adverbs

While many adjectives can be formed with the suffix “-ar,” it’s important to note that the suffix “-er” is the only ending that can be used to create comparative adjectives and comparative adverbs—adjectives and adverbs used to compare traits between two people or things. For example:
  • bright→brighter
  • dim→dimmer
  • fast→faster
  • full→fuller
  • happy→happier
  • long→longer
  • red→redder
  • slow→slower
  • tall→taller
  • witty→wittier

Forming other comparatives

Note that not all adjectives can become comparative by adding “-er.” Only those that have one syllable or those with two syllables ending in “-y” can do so. For longer adjectives, we simply add the words more or less before them, as in:
  • admirable→more/less admirable
  • careful→more/less careful
  • intelligent→more/less intelligent
  • loyal→more/less loyal
  • respectful→more/less respectful
  • vivid→more/less vivid
Adverbs also have this restriction, though it is only single-syllable adverbs that can take the “-er” suffix; adverbs ending in “-y” are almost always formed by adding “-ly” to adjectives, and they take the words more/less to become comparative. For example:
  • admirably→more/less admirably
  • carefully→more/less carefully
  • intelligently→more/less intelligently
  • loyally→more/less loyally
  • respectfully→more/less respectfully
  • vividly→more/less vividly
Other adjectives are simply irregular, and have a specific comparative form that does not follow the convention above; here are some of the most common examples:
fun→more/less fun
far→farther (literal distance) or further (figurative distance)
little→less (when describing an amount)
far→farther (literal distance) or further (figurative distance)
little→less (when describing an amount)
(*Early is both an adjective and an adverb, and it has the same comparative form in both uses: earlier. This is irregular only as an adverb because it goes against the convention of adding more/less to adverbs ending in “-ly.”)

1. Which of the following suffixes is most commonly used to form nouns from verbs?

2. Which of the following suffixes is least commonly used to form nouns from verbs?

3. In which of the following instances would we most likely use the suffix “-or”?

4. Which of the following verbs takes the “-er” suffix to become a noun of agency?

5. Which part of speech is most commonly formed with the suffix “-ar”?

6. Which of the following suffixes is used to form comparative adjectives and adverbs?

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