ies

ies is the common plural suffix for many English nouns that end in -y when the letter before the y is a consonant. In these cases the final -y is replaced by -ies to form the plural. For example: party becomes parties, city becomes cities, baby becomes babies, and lady becomes ladies.

If the -y is preceded by a vowel, the usual plural is formed by simply adding -s, and the y is not changed. Examples include day → days, toy → toys, and valley → valleys. Some words ending in -ey or -oy with a preceding vowel follow the same pattern, resulting in forms like money → monies or joys (depending on standard usage in the context), and many other regular plurals simply take -s.

There are exceptions and irregular cases. A well-known irregular plural is die → dice, where the -y rule does not apply. Words that end in -ie or -ye do not always take -ies in the plural; for example, movie → movies, and hobby → hobbies (the latter is regular because the y follows a consonant). Additionally, some words borrowed from other languages retain spellings that do not fit the -ies rule.

Overall, the -ies ending is a productive and widely used pattern in modern English, aligning spelling with the consonant+ y rule for plural formation and helping distinguish certain word forms in both everyday and formal writing.