Boo Very Common

a cry or noise made to express displeasure or contempt

"The crowd let out a loud boo when they saw the referee make such an obvious mistake."

A derisive shout made to indicate disapproval.

"He was banned from the house party for bringing a small amount of boo to share with his friends."

A close acquaintance or significant other.

Cannabis.

show displeasure, as after a performance or speech

"The audience booed loudly when the comedian forgot his opening joke and stumbled over his first line."

To shout extended boos derisively.

"The curious calf began to boo at its mother as she walked away into the field."

To make a sound characteristic of cattle; to moo.

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.

"I hid behind the door and jumped out just as my little brother walked in to say boo."

A locality in Nacka, Stockholm, central Sweden.

"While traveling through Nigeria, my guide taught me to say boo as a friendly greeting in the local Boko language."

The Boko language.