A Boo is a type of ghost featured in Mario video games. Boos made their first appearance under the name of "Boo Diddly"(a play on Bo Diddley an early R&Bguitarist) in Super Mario Bros. 3 and was virtually invincible to all attacks with the exception of the Starman and the Hammer Bros. Suit.
by TheBlackMew September 7, 2006

Boo is a hamster who serves as the animal companion of the berserk ranger Minsc from the Baldur's Gate series of computer games. Minsc claims Boo is a miniature giant space hamster.
by Jason Attard October 22, 2004

"BOO!"
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
by SLAP 'NOTHER CLAM ON THERE April 28, 2022

A scary ghost creature in the Mushroom Kingdom. Mario faces these a lot. These pearly-white ghosts will become invisible if anyone faces them. They usually cannot be disposed of. There are also other Boos, like the Big Boo, King Boo, and more.
by SeaCaptainDrake December 6, 2003

by Patricia Reyes December 14, 2008

The one. The one who will always be there for you no matter what the circumstances may be. If you have someone special...call them boo ^_^
"You're everything to me. I love you Boo"
by Tasher March 25, 2008

by Jason Bond 86 April 23, 2009
