What is the meaning of Boo?

A loud exclamation intended to scare someone. Usually used when one has been hidden from the target, and then appears unexpectedly.

An exclamation used by a member of an audience, as at a stage play or sporting event, to indicate derision or disapproval.

A derisive shout made to indicate disapproval.

To shout extended boos derisively.

To shout extended boos at, as a form of derision.

A close acquaintance or significant other.

Cannabis.

To make a sound characteristic of cattle; to moo.

A tail feather from an ostrich.

moon

Boo

to cry aloud, bellow, roar; bray

to call loudly upon; bellow, cry or roar forth

to bow, to stoop

to bend, to curve

to make something bend or curve

a bow (of greeting)

Obsolete spelling of buo.

Obsolete spelling of buo.

Source: wiktionary.org