The word cheer can be used as a noun:
cheer
noun
a shout of joy, support or praiseA great cheer went up from the crowd.
Or as a verb:
cheer
verb
to shout loudly, to show support or praise for somebody, or to give them encouragementWe all cheered as the team came on to the field.
Sometimes we don’t want to cheer, we want to do the opposite. Do you know the opposite of cheer? It’s boo!
Boo also has 2 forms:
boo
exclamation, noun
a sound that people make to show that they do not like an actor, speaker, etc‘Boo!’ they shouted, ‘Get off!’We also shout ‘Boo!’ when we want to scare someone.
Or as a verb:
boo
verb
to show that you do not like a person, performance, idea, etc. by shouting ‘boo’The audience booed as she started her speech.