wild card (n.)

Old English wilde "in the natural state, uncultivated, untamed, undomesticated, uncontrolled," from Proto-Germanic *wildia- (source also of Old Saxon wildi, Old Norse villr, Old Frisian wilde, Dutch wild, Old High German wildi, German wild, Gothic wilþeis "wild," German Wild (n.) "game"), of uncertain origin, perhaps from PIE root *welt- "woodlands; wild" (see wold).

Ursula ... hath bin at all the Salsbury rasis, dancing like wild with Mr Clarks. [letter, 1674]

Meaning "sexually dissolute, loose" is attested from mid-13c. Meaning "distracted with excitement or emotion, crazy" is from 1590s. U.S. slang sense of "exciting, excellent" is recorded from 1955. As an adverb from 1540s. Baseball wild pitch is recorded from 1867. Wildest dreams attested from 1717. Wild West in a U.S. context recorded by 1826. Wild Turkey brand of whiskey (Austin Nichols Co.) in use from 1942.

early 15c., "a playing card," from Old French carte (14c.), from Medieval Latin carta/charta "a card, paper; a writing, a charter," from Latin charta "leaf of paper, a writing, tablet," from Greek khartēs "layer of papyrus," which is probably from Egyptian. Form influenced by Italian cognate carta "paper, leaf of paper." Compare chart (n.). The shift in English from -t to -d is unexplained.

Sense of "playing cards" also is oldest in French. Sense in English extended by 1590s to similar small, flat, stiff pieces of paper. As "small piece of cardboard upon which is written or printed the name, address, etc. of the person presenting it" is from 1795, visiting-cards for social calls, business-cards announcing one's profession. Meaning "printed ornamental greetings for special occasions" is from 1862.

Application to clever or original persons (1836, originally with an adjective, as in smart card) is from the playing-card sense, via expressions such as sure card "an expedient certain to attain an object" (c. 1560).

Card-sharper "professional cheat at cards" is from 1859. House of cards in the figurative sense "any insecure or flimsy scheme" is from 1640s, first attested in Milton, from children's play. To (figuratively) have a card up (one's) sleeve is from 1898. To play the _______ card (for political advantage) is from 1886, originally the Orange card, meaning "appeal to Northern Irish Protestant sentiment."

Cards are first mentioned in Spain in 1371, described in detail in Switzerland in 1377, and by 1380 reliably reported from places as far apart as Florence, Basle, Regensburg, Brabant, Paris, and Barcelona. References are also claimed for earlier dates, but these are relatively sparse and do not withstand scrutiny. [David Parlett, "A History of Card Games"]