"having many names or terms," 1610s, from Late Latin multinominis "many-named," from multi- "many" (see multi-) + Latin nomen (genitive nominis) "name," cognate with Old English nama (from PIE root *no-men- "name"). 

"bringing forth many young at a birth," 1640s, from Modern Latin multiparus "giving or having given birth to many," from multi- "many" + stem of parire "to bring forth" (from PIE root *pere- (1) "to produce, procure"). Related: Multiparity.

also multi-lateral, 1690s, in geometry, "having many sides," from multi- "many" + lateral (adj.). Figurative use, "many-sided," is by 1748. Meaning "pertaining to three or more countries" is from 1802 (based on bilateral). Related: Multilaterally.

"turning into many shapes, protean," 1828, from multi- "many" + present participle of Latin versare, literally "to turn often" (see versant).

"inhabited by or containing many races or nationalities," 1885, in reference to Austria-Hungary, from poly- "many" + ethnic (adj.).

also multi-partite, 1721, "divided into many parts," from Latin multipartitus "divided into many parts," from multi- "many" (see multi-) + partitus, past participle of partire "to divide" (from pars "a part, piece, a share," from PIE root *pere- (2) "to grant, allot").

"entertainment in which one actor performs as many characters," by 1824; see mono- "one, single" + poly- "many" + -logue.

in botany, "bearing many (more than three) flowers," 1834, from Late Latin multiflorus "many-flowered" (see multiflora) + -al (1).

"having or exhibiting many or various forms," 1785, from Greek polymorphos "multiform, of many forms, manifold," from polys "many" (from PIE root *pele- (1) "to fill") + morphē "shape, form," a word of uncertain etymology. Especially of insects: "undergoing a series of marked changes during development." Related: Polymorphic; polymorphously; polymorphousness.

1780, "condition of having many wives, marriage or cohabitation of one man with more than one woman at the same time," from Greek polygynēs "having many wives," from polys "many" (see poly-) + gynē "woman, wife" (from PIE root *gwen- "woman"). Related: Polygynous.