The part of speech indicates how the word functions in meaning as well as grammatically within the sentence. An individual word can function as more than one part of speech when used in different circumstances.
Category: Noun

Irregular Plural Noun
Irregular plural nouns are nouns that do not become plural by adding -s or -es, as most nouns in the English language do.

Regular Plural Noun
Regular Plural nouns are nouns that represent more than one person, place, thing, or idea. Plural nouns are formed from singular nouns by adding an –s at the end.