The crossword solution for the term 'Monsters, Inc.' is 'BOO, ' a three-letter word. BOO is the name of the little girl in the 2001 Pixar animated film, Monsters, Inc. She is a human child who accidentally enters the monster world and befriends Sulley and Mike, two monsters who work at Monsters, Inc. Sulley and Mike must protect BOO from the evil Randall, who wants to capture her and use her to generate fear.