S: (n) 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))
S: (n) stamp (a type or class) "more men of his stamp are needed"
S: (n) sex (either of the two categories (male or female) into which most organisms are divided) "the war between the sexes"
S: (n) 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"
S: (n) conjugation (a class of verbs having the same inflectional forms)
S: (n) 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"
S: (n) 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)
S: (n) coupling, mating, pairing, conjugation, union, sexual union (the act of pairing a male and female for reproductive purposes) "the casual couplings of adolescents"; "the mating of some species occurs only in the spring"
S: (n) union, unification, uniting, conjugation, jointure (the act of making or becoming a single unit) "the union of opposing factions"; "he looked forward to the unification of his family for the holidays"