—int.
1 an expression of disapproval or contempt.
2 a sound, made esp. to a child, intended to surprise.
—n. an utterance of boo, esp. as an expression of disapproval or contempt made to a performer etc.
—v. (boos, booed)
1 intr. utter a boo or boos.
2 tr. jeer at (a performer etc.) by booing.
Phrases and idioms:
can't (or wouldn't) say boo to a goose is very shy or timid.
Etymology: imit.
Useful english dictionary. 2012.