kind,
sort,
variety,
form a category of things distinguished by some common characteristic or quality; "sculpture is a form of art"; "what kinds of desserts are there?"
substitution class,
paradigm the class of all items that can be substituted into the same position (or slot) in a grammatical sentence (are in paradigmatic relation with one another)
brass family (music) the family of brass instruments
violin family (music) the family of bowed stringed instruments
stamp a block or die used to imprint a mark or design
sex the properties that distinguish organisms on the basis of their reproductive roles; "she didn't want to know the sex of the foetus"
declension a class of nouns or pronouns or adjectives in Indo-European languages having the same (or very similar) inflectional forms; "the first declension in Latin"
conjugation a class of verbs having the same inflectional forms
denomination a class of one kind of unit in a system of numbers or measures or weights or money; "he flashed a fistful of bills of large denominations"
histocompatibility complex a family of fifty or more genes on the sixth human chromosome that code for proteins on the surfaces of cells and that play a role in the immune response