BOO

I. interjection Etymology: Middle English bo Date: 15th century — used to express contempt or disapproval or to startle or frighten II. noun (plural ~s) Date: 1801 a shout of disapproval or contempt, any utterance at all, III. verb Date: 1884 intransitive verb to deride especially by uttering a prolonged ~ , transitive verb to express disapproval of by ~ing