Having a strong effect on someone or something; forceful; powerful.
Exceptionally good; spectacular, impressive, etc.
The definition of kick ass is something that is really impressive or powerful.
An example of kick ass is a great new sports car.
(slang) Used to express happiness or a feeling of accomplishment.
Kick ass! I just got my friend to stop playing that stupid song!
The Mega Man X soundtrack really kicks ass!
(idiomatic, US, Canada, colloquial) To beat someone in a fight.