cardboard n.

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. The form has been influenced by Italian cognate carta "paper, leaf of paper." Compare chart (n.). The shift in English from -t to -d is unexplained.

The sense of "playing cards" also is the oldest of the French word. The sense in English was 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," from 1795: visiting-cards for social calls, business-cards announcing one's profession. The 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"]

"piece of timber sawn flat and thin, longer than it is wide, wider than it is thick, narrower than a plank;" Old English bord "a plank, flat surface," from Proto-Germanic *burdam (source also of Old Norse borð "plank," Dutch bord "board," Gothic fotu-baurd "foot-stool," German Brett "plank"), perhaps from a PIE verb meaning "to cut." See also board (n.2), with which this is so confused as practically to form one word (if indeed they were not the same word all along).

In late Old English or early Middle English the sense was extended to include "table;" hence the transferred meaning "food" (early 14c.), as "that which is served upon a table," especially "daily meals provided at a place of lodging" (late 14c.). Compare boarder, boarding, and Old Norse borð, which also had a secondary sense of "table" and an extended sense "maintenance at table." Hence also above board "honest, open" (1610s; compare modern under the table "dishonest").

A further extension was to "table where council is held" (1570s), from whence the word was transferred to "leadership council, persons having the management of some public or private concern" (1610s), as in board of directors (1712).

"Bow to the board," said Bumble. Oliver brushed away two or three tears that were lingering in his eyes; and seeing no board but the table, fortunately bowed to that.

The meaning "table upon which public notices are written" is from mid-14c. The meaning "table upon which a game is played" is from late 14c. The sense of "thick, stiff paper" is from 1530s. Boards "stage of a theater" is from 1768.