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.
c. 1600, "uncouple" (a sense now obsolete), from French découpler "to uncouple," from dé- (see de-) + coupler (Old French copler; see couple (v.)). In modern use, "to make the coupling of two electrical systems very loose." Related: Decoupled; decoupling.
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.