Adding Endings to Words that End in “-y”
When adding endings to words that end with a consonant plus -y, change the final y to i (unless the ending in question, such as -ish, already begins with an i).
- pretty: prettier / prettiest
- ready: readily
- beauty: beautiful
This rule also applies when adding the -s, -ed, and -ing endings to verbs ending in -y.
- defy: defies / defying / defied
- apply: applies / applying / applied
Adapted from: Oxford Dictionaries: Spelling Rules and Tips (http://www.oxforddictionaries.com/words/spelling-rules-and-tips)