Changing Y to I with Suffixes  

The letter Y is often referred to as a semi-vowel because it can behave as either a vowel or a consonant depending on its position and function in a word. When it appears at the end of a word, Y is always considered a vowel because it creates a vowel sound.

Changing Y to I before a suffix

However, a final Y isn’t flexible in the way it is pronounced, and it doesn’t function well with other letters when a suffix is attached. In most cases, we must change it to the letter I, which makes the word easier to read and pronounce. This is generally true for both vowel and consonant suffixes. For example:
With Vowel Suffixes
With Consonant Suffixes
apply→appliance, applied, applies
beauty→beautify, beautiful
colony→colonial, colonies, colonize
contrary→contrarily, contrariness, contrariwise
envy→enviable, envied, envious
eery→eerily, eeriness
happy→happier, happiest
happy→happily, happiness
luxury→luxuriant, luxuriate, luxurious
likely→likelihood, likeliness
marry→marriage, married, marries
merry→merrily, merriment, merriness
pity→pitiable, pities
pity→pitiful, pitiless
tidy→tidied, tidier, tidiest
trustworthy→trustworthily, trustworthiness
worry→worried, worrier, worries
weary→weariful, weariness, wearisome

Exception 1: Don’t change Y to I before “-ing”

You may have noticed that none of the words above featured the ending “-ing.” This is because we never change Y to I when it is followed by this suffix. To maintain the meaning of the word with “-ing,” we need to keep the syllable that Y provides. We can’t have a word ending in IING (unless the root word ends in I, as in skiing or taxiing), and if we simply replace Y with “-ing,” the meaning of the word will change (or seem to change).
Let’s look at the examples from above again, this time adding “-ing”:
Root Word
Correctly Suffixed Word
Incorrectly Suffixed Words
apply
applying
appling, appliing
envy
envying
enving, enviing
marry
marrying
marring, marriing
pity
pitying
piting, pitiing
tidy
tidying
tiding, tidiing
worry
worrying
worring, worriing

Exception 2: shy, sly, spry, wry

For these single-syllable adjective words, it is preferred to keep the Y when a suffix is added to make them into adverbs, nouns, or comparative/superlative adjectives. While the words can be spelled with an I, this is usually seen as an acceptable (but less common) variant. Note, however, that with the suffix “-ness” (and in some cases “-ly”), Y is always kept. For example:
Root Word
Preferred Suffix Spellings
Variant Suffix Spellings
Incorrect Suffix Spellings
shy
shyer, shyest, shyly, shyness
shier, shiest, shily (now rare)
shiness
sly
slyer, slyest, slyly, slyness
slier, sliest, slily
sliness
spry
spryer, spryest, spryly, spryness
sprier, spriest
spriness
wry
wryer, wryest, wryly, wryness
wrier, wriest
wrily, wriness

Sub-exception 1: shy, shies, shied, shying

Note that the word shy can also function as a verb, which means that it can take other inflectional suffixes to conjugate for tense, aspect, and grammatical person. Like all words ending in Y, the suffix “-ing” (which indicates the present participle form) attaches to shy with no other change in spelling: shying.
However, when it is put into the simple past tense or the first-person singular, Y is changed to I: shied, shies. Unlike with other vowel suffixes, this altered spelling is the only one that is correct; we can’t keep Y with “-ed” or “-es.”
Note that this pattern also applies to other regular single-syllable verbs ending in a consonant + Y:
  • cry→ cries, cried, crying
  • dry→ dries, dried, drying
  • fry→ fries, fried, frying
  • ply→ plies, plied, plying
  • try→ tries, tried, trying

Sub-exception 2: dryer vs. drier

Like the other single-syllable words we just looked at, the word dry will in some cases keep its Y and other times have it replaced with I. However, there are specific instances for each, depending on the meaning of the root word.
For example, when dry is an adjective meaning “not wet,” we replace Y with I to form the comparative adjective drier (we do the same thing to form the superlative adjective driest). However, when dry is a verb meaning “to make or become not wet,” we keep Y to form the noun dryer (“a machine that makes things dry”). Both forms are considered acceptable for each meaning, but keeping the spellings distinct like this helps make your meaning clearer to the reader.
In addition, as we saw at the end of the previous sub-exception, there are certain ways we must spell the word dry, especially when it is being conjugated as a verb. Take a look at the table below to see all the various ways we add suffixes to dry:
Replace Y with I
(preferred)
Don’t replace Y with I
(preferred)
Y is always replaced with I
Y is never replaced with I
drier
(comparative adjective)
driest
(superlative adjective)
dryer
(noun of agency)
dryly
(adverb)
dried
(simple past tense)
dryness
(noun of quality)

Exception 3: Don’t change Y to I when it comes after a vowel

When Y comes after another vowel at the end of a word, we do not change it to an I regardless of the type of suffix that attaches to it.
For example:
Root Word
Correctly Suffixed Words
Incorrectly Suffixed Words
annoy
annoyance, annoyed, annoys
annoiance, annoied, annoies
buy
buyable, buyer, buys
buiable, buier, buies
convey
conveyance, conveyer, conveyor
conveiance, conveier, conveior
deploy
deployable, deployed, deployment
deploiable, deploied, deploiment
joy
joyful, joyless, joyous
joiful, joiless, joious
play
played, player, playful
plaied, plaier, plaiful
toy
toyed, toyish, toyless
toied, toiish, toiless

Irregular verbs ending in a vowel + Y

Be careful of the exception we just looked at, however: several verbs ending in a vowel (especially A) + Y have irregular conjugations for the past tense, meaning their past tense and past participle forms aren’t formed by adding “-ed.” Unfortunately, we just have to memorize which verbs are irregular and how they are conjugated. For example:
Root Word
Irregular Form(s)
Incorrect Form
buy
bought
buyed
lay
laid
layed
may
might
mayed
pay*
(to spend money)
paid
payed
say
said
sayed
slay
(to kill)
slew, slain
slayed**
(*The most common meanings of the word pay—having to do with spending or yielding money or profits—form the irregular past tense paid. However, a less common nautical meaning of the verb—to cover with pitch or tar—does have a regular past-tense form: payed.)
(**Through colloquial usage, slayed is becoming an acceptable past tense/past participle form for slay, especially because another meaning of the word—“to amuse”—does take the regular form slayed.)
Quiz

1. In general, Y is changed to I before which types of suffixes?





2. Which of the following suffixes never results in Y changing to I?





3. Which of the following suffixed words is spelled incorrectly?





4. Which of the following suffixed words is spelled correctly?





5. When we add the suffix “-ly,” the preferred spelling is to keep Y for which of the following words?





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