aboveboard (adj.)

Middle English above, aboven (also aboun in northern dialects, abow in southwestern dialects), from Old English abufan (adv., prep.), earlier onbufan "above, in or to a higher place, on the upper side; directly over, in or to a higher place than," a contraction or compound of on (also see a- (1)) + bufan "over."

The second element is itself a compound of be "by" (see by) + ufan "over/high" (from Proto-Germanic *ufan-, source also of Old Saxon, Old High German oban, German oben; from PIE root *upo "under," also "up from under," hence also "over").

From c. 1200 as "of higher rank or position, superior in authority or power; of higher rank than, superior to." This sense in Middle English perhaps was reinforced by a literal use of above in the sense "higher at the table than," thus "in a place of greater honor than, taking precedence over" (mid-14c.) From mid-14c. as "in addition to;" also "superior to, out of reach of, not condescending to." From late 14c. as "more" (in number, linear measurement, weight, value); "older; better than, more desirable than, superior to."

Phrase above all "before other considerations" is from late 14c. To be above (someone's) head in the figurative sense "out of range of his or her intellect" is from 1914 (above in the sense "not to be grasped or understood by" is from mid-14c.). In Middle English to be above erthe was "above ground, unburied," hence "living, among the living."

"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.