SUITABLE›of a good enough quality or suitable type for a particular purpose: [+ to do sth]Is this water fit to drink?She's not in a fit state to drive.
HEALTH›healthy, especially because you exercise regularly: He's very fit for his age. → Oppositeunfit
do sth as you see/think fit›to do something that you feel is the right thing to do, although other people might disapprove: You must spend the money as you see fit.