Collins COBUILD Advanced Learner's English Dictionary - boo

(boos, booing, booed) 1. If you boo a speaker or performer, you shout ‘boo’ or make other loud sounds to indicate that you do not like them, their opinions, or their performance. People were booing and throwing things at them... Demonstrators booed and jeered him... He was booed off the stage. VERB: V, V n, be V-ed • Boo is also a noun. She was greeted with boos and hisses. N-COUNT: usu pl • booing The fans are entitled to their opinion but booing doesn’t help anyone. N-UNCOUNT 2. You say ‘Boo!’ loudly and suddenly when you want to surprise someone who does not know that you are there. EXCLAM 3. see also peekaboo