if somethings kick ass, its really cool. Great! As in it kicks the ass of all else. It can be inanimate and still kick ass. lol- inanimate, like busted's career

Verb: To be really, really, really cool. <present tense>

1)(v) to actually physically hurt someone, however you will usually hear a pronoun in between kick and ass in this definition
2)(adj.)very very cool or awesome
3)(v) to be in the process of kicking ass

Intransitive verb. To win in a fight without contest. Derived from (rare) to send the opponent on the run and deliver a parting blow with one's foot at the decisive conclusion.
Adjective. The ability to win in a fight or argument without contest.
Noun. By extension, anything that would rock hard enough to win in a fight or as the subject of an argument.

1)to harm, cause physical damage to;beat up
2) an interjection used in times of joy

(Adjective/Interjection) Very exciting or fun. Possibly derived from the phrase "better than a kick in the ass".

kick ass- to beat someone's butt @ something