When a word ends in a vowel plus “-y,” it’s usually easy to modify it by adding a letter (or letters): adding “-ous,” for example, means “joy” becomes “joyous.”
However, when a word ends in a consonant plus “y” things get more complicated, which can make spelling challenging. To ensure your written work is error-free, it helps to keep the “y” to “i” rule in mind.
The “Y” to “I” Rule
The basic rule is, for any word that ends in a consonant plus “-y,” change the “y” to “i” if adding a suffix or forming a plural.
Plurals
For plurals, simply change the “y” to an “-ies”:
Singular |
Plural |
Story |
Stories |
Candy |
Candies |
Hippy |
Hippies |
First-Person Singular and Past Tense Verbs
Forming the first-person singular of a verb ending in a consonant plus “y” requires changing the “y” to “-ies.” while the past tense involves switching “y” for “-ied”:
Verb |
First-Person Singular |
Past Tense |
Fry |
Fries |
Fried |
Apply |
Applies |
Applied |
Beautify |
Beautifies |
Beautified |
Comparatives and Superlatives
When an adjective ends in a consonant plus “-y,” forming a comparative or superlative involves changing the “y” to “-ier” and “-iest” respectively:
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Adjective |
Comparative |
Superlative |
Tiny |
Tinier |
Tiniest |
Jumpy |
Jumpier |
Jumpiest |
Thirsty |
Thirstier |
Thirstiest |
Forming Adverbs
Modifying an adjective to make an adverb involves substituting the “y” for “-ily”:
Adjective |
Adverb |
Happy |
Happily |
Lazy |
Lazily |
Flimsy |
Flimsily |
Exceptions
The “y”-to-“i” rule doesn’t always work; some variations of “sly,” for example, can be spelled with either a “y” or an “i” (e.g., “slyest/sliest” and “slyer/slier”).
Moreover, while changing “y” to “i” isn’t typically necessary when a word ends with a vowel plus “-y,” there are exceptions here too (such as modifying “day” to become “daily”).
As such, although the “y” to “i” rule is a good guideline, it’s still important to double-check words if you’re not sure they’re spelled correctly.