WordWeb Online

1. Show displeasure, as after a performance or speech
   - hiss

1. A cry or noise made to express displeasure or contempt
   - hoot, Bronx cheer [N. Amer], hiss, raspberry, razzing [N. Amer], razz [N. Amer], snort, bird

1. Exclamation used to startle or frighten
    
2. Expressing disapproval

Derived forms: booed, boos, booing

Type of: call, condemn, cry, outcry, shout, vociferation, yell

Antonym: applaud

Encyclopedia: Boo Boo, Sweden