Meaning of “fitness” - Learner’s Dictionary

fitness

noun [ U ] uk us /ˈfɪtnəs/
HEALTHY

B1 the condition of being physically strong and healthy:

physical fitness
SUITABLE

the quality of being suitable for a particular purpose, job, course of study, etc:

The purpose of the exercise is to judge a soldier's fitness for combat.

(Definition of “fitness” from the Cambridge Learner’s Dictionary © Cambridge University Press)