"long pole," 1540s, from Scottish boun, borrowed from Du. boom "tree, pole, beam," from a M.Du. word analogous to O.E. beam (see beam
). The business sense (1873) is sometimes said to be from this word, from the nautical meaning "a long spar run out to extend the foot of a
sail;" a ship "booming" being one in full sail. But it could just as well be from boom
(v.), on the notion of "suddenness."