Lewis & Short

conjŭgātĭo, ōnis, f. [conjugo] (except twice in Cic. Top. only post-class.),

  1. I. a combining, connecting; hence, prop., a mingling, mixture: mellis et fellis, App. Flor. 4, n. 18, p. 359, 29: corporum, carnal intercourse, coition, Arn. 2, 54: uxoria, id. 5, 171: ursi velut humanis conjugationibus copulantur, Sol. 26, 3.
  2. II. Esp., t. t.
    1. A. In rhet., the etymological relationship of words, Gr. συζυγία, Cic. Top. 3, 12; 9, 38.
    2. B. In later gram., conjugation; earlier called declinatio, q. v.; Mart. Cap. 3, § 311; Commian. ap. Charis. p. 153 P.; Diom. p. 337 ib.; Prisc. p. 836 et saep.
    3. C. In logic, a syllogism: propositionum, App. Dogm. Plat. p. 35.