Meaning of form class

form' class"

Pronunciation: [key]
— Gram. Gram.
  1. a class of words or forms in a given language that have one or more grammatical features in common, as, in Latin, all masculine nouns in the nominative singular, all masculine singular nouns, all masculine nouns, or all nouns.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.