sideboard (n.)

late Old English, "long, broad, spacious; extending lengthwise," from side (n.). Compare Old Norse siðr "long, hanging down." From late 14c. as "being from or toward the side," hence also "subordinate." Also "apart from the main course" of anything, as in side-road (1854); side-trip (1911). In side-eye (by 1922) the notion is "directed sideways."

"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.

"an Italian sideboard," 1883, from Italian credenza, literally "belief, credit," from Medieval Latin credentia (see credence).

The same evolution that produced this sense in Italian also worked on the English word credence, which in Middle English also meant "act or process of testing the nature or character of food before serving it as a precaution against poison," a former practice in some royal or noble households. Because of that, it also meant "a side-table or side-board on which the food was placed to be tasted before serving" (mid-15c.); hence, in later use, "a cupboard or cabinet for the display of plate, etc." (1560s). These senses fell away in English, and the modern furniture piece, which begins to be mentioned in domestic interiors from c. 1920, took its name from Italian, perhaps as a more elegant word than homely sideboard.