Please refer to 4c & 4d under transitive verb, as well as, 2 & 3 under intransitive verb.
Full Definition of quit
quit also quit·tedquit·ting
transitive verb
1
: to make full payment of : pay up <quit a debt>
2
: to set free : relieve, release <quit oneself of fear>
3
: conduct, acquit <the youths quit themselves like men>
4
a : to depart from or out of b : to leave the company of c : give up 1 <quit a job> d : give up 2 <quit smoking>
intransitive verb
1
: to cease normal, expected, or necessary action <the engine quit>
2
: to give up employment
3
: to admit defeat : give up
I have decided to give up arguing about this. Or am I quitting? I have no idea anymore.