late 14c., "a joining or meeting of individuals or distinct things," originally of planets or stars "meeting" in the same part of the sky, from Old French conjonction "union, joining, sexual intercourse" (12c.), from Latin coniunctionem (nominative coniunctio), noun of action from past-participle stem of coniugare "to join together," from assimilated form of com "with, together" (see con-) + iugare "to join," from iugum "yoke" (from PIE root *yeug- "to join").
Compare Italian congiunzione, Spanish conjunción, from the same Latin noun. The English word also had the meaning "sexual union" 17c.-18c. Old English used geðeodnys as a loan-translation of Latin coniunctio.
Grammatical sense of "connective particle serving to unite clauses of a sentence or coordinate words in a clause or sentence" (late 14c.) was in Latin, a loan-translation of Greek syndesmos.
"conjunction or opposition of a heavenly body with the sun," 1650s, from Late Latin syzygia, from Greek syzygia "yoke of animals, pair, union of two, conjunction," from syzygein "to yoke together," from assimilated form of syn- "together" (see syn-) + zygon "yoke" (from PIE root *yeug- "to join"). Related: Syzygial; Syzygiacal; Syzygetic.
"a word viewed as a constituent member of a sentence," c. 1500, translating Latin pars orationis (see parse). The parts of speech are: Noun, adjective, pronoun, verb, adverb, preposition, conjunction, and interjection. Sometimes article and participle are counted among them.
"at time past" (archaic), c. 1200, from Old English hwilum "at times," dative case of while (q.v.). As a conjunction from 1610s. Similar formation in German weiland "formerly."
"with or on condition that; this (or it) being understood, conceded, or established," early 15c., conjunction use of past participle of provide. As an adjective, "destined" (early 15c.); "prepared, ready" (1570s); "furnished" (1878).
1550s, "to harness beasts in a team," from team (n.). From 1841 as "drive a team." The meaning "to come together as a team" (usually with up) is attested from 1932. Transitive sense "to use (something) in conjunction" (with something else) is from 1948. Related: Teamed; teaming. The Old English verb, teaman, tieman, is attested only in the sense "bring forth, beget, engender, propagate."