∙ A loud exclamation intended to scare someone, especially a child. Usually used when one has been hidden from the victim and then suddenly appeared unexpectedly.
∙ A word used ironically in a situation where one might have scared someone, but said someone was not scared. Not said as loudly as in definition 1.
∙ An exclamation used by a member or many members of an audience, as at a stage play or sports game, to indicate derision or disapproval of what has just occurred.
Noun
∙ A derisive shout made to indicate disapproval.
Verb
∙ To shout extended boos derisively. intransitive
∙ To derisively shout extended boos at. transitive
Noun
∙ A close acquaintance or significant other. US, African American Vernacular, slang
Boo
Proper noun
∙ A locality situated in Nacka Municipality, Stockholm County, Sweden.