1the condition of being physically fit and healthy:disease and lack of fitness are closely related [as modifier]:a fitness test
Biology an organism’s ability to survive and reproduce in a particular environment:if sharp teeth increase fitness, then genes causing teeth to be sharp will increase in frequency
2 (fitness for/to do) the quality of being suitable to fulfil a particular role or task:the medical board assessed his fitness for active service
fitness in other Oxford dictionaries
Definition of fitness in the US English dictionary
