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.
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. 1300, pouer, "ability; ability to act or do; strength, vigor, might," especially in battle; "efficacy; control, mastery, lordship, dominion, ability or right to command or control; legal power or authority; authorization; military force, an army," from Anglo-French pouair, Old French povoir, noun use of the infinitive, "to be able," earlier podir (9c.), from Vulgar Latin *potere (source also of Spanish poder, Italian potere), from Latin potis "powerful" (from PIE root *poti- "powerful; lord").
Whatever some hypocritical ministers of government may say about it, power is the greatest of all pleasures. It seems to me that only love can beat it, and love is a happy illness that can't be picked up as easily as a Ministry. [Stendhal "de l'Amour," 1822]
Meaning "one who has power, person in authority or exercising great influence in a community" is late 14c. Meaning "a specific ability or capacity" is from early 15c. In mechanics, "that with which work can be done," by 1727.
Sense of "property of an inanimate thing or agency of modifying other things" is by 1590s. Meaning "a state or nation with regard to international authority or influence" [OED] is from 1726. Meaning "energy available for work is from 1727. Sense of "electrical supply" is from 1896.
Colloquial a power of for "a large quantity of, a great number of" is from 1660s (compare powerful). Phrase the powers that be "the authorities concerned" is from Romans xiii.1. As a statement wishing good luck, more power to(someone) is recorded from 1842. A man-advantage power play in ice hockey so called by 1940. Power failure "failure of the (electrical) power supply" is from 1911; power steering in a motor vehicle is from 1921. Power politics "political action based on or backed by threats of force" (1937) translates German Macht-politik.
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.