healthy and strong, especially because you do regular physical exercise Top athletes have to be very fit. fit (to do something) He won't be fit to play in the match on Saturday. She tries to keep fit by jogging every day. fit (for something) (British English) He's had a bad cold and isn't fit enough for work yet. I feel really fighting fit (= very healthy and full of energy). The government aims to make British industry leaner and fitter (= employing fewer people and with lower costs).