late 13c., "two of the same kind or class connected or considered together," especially "a man and a woman associated together by marriage or love," from Old French cople "married couple, lovers" (12c., Modern French couple), from Latin copula "tie, connection," from PIE *ko-ap-, from *ko(m)- "together" + *ap- "to take, reach."
From mid-14c. as "that which unites two." In electricity, "pair of connected plates of different metals used for creating a current," from 1863.
c. 1200, "to link or connect, as one thing with another," from Old French copler "to couple, join together," from cople (see couple (n.)). Meaning "unite in marriage" is from mid-14c.; that of "embrace sexually, copulate" is from c. 1400. Related: Coupled; coupling.
mid-14c., "the joining of one thing to another," verbal noun from couple (v.). From late 14c. as "the joining of two persons in love or marriage," also "copulation." Meaning "that which couples or connects" is from 1540s.
1570s, in poetry, "two lines in succession, forming a pair and generally rhyming with one another," from French couplet (mid-14c.), a diminutive of couple (see couple (n.)). Earlier in the same sense was couple (mid-14c.). In music, from 1876.
early 15c., "act of comparing," from Latin comparationem (nominative comparatio) "a putting together," hence, "a comparing," noun of action from past participle stem of comparare "to couple together" (see comparison).
