n. & v.
n. 1 an owl's cry. 2 the sound made by a motor horn or a steam whistle. 3 a shout expressing scorn or disapproval; an inarticulate shout. 4 colloq. a laughter. b a cause of this. 5 (also two hoots) sl. anything at all (don't care a hoot; don't give a hoot; doesn't matter two hoots).
v. 1 intr. a (of an owl) utter its cry. b (of a motor horn or steam whistle) make a hoot. c (often foll. by at) make loud sounds, esp. of scorn or disapproval or colloq. merriment (hooted with laughter). 2 tr. a assail with scornful shouts. b (often foll. by out, away) drive away by hooting. 3 tr. sound (a motor horn or steam whistle).
[ ME huten (v.), perh. imit. ]