What is the definition of fitness in biology?

Answer 1

'Fitness' is used in relation to exercise, diet and overall well-being. In terms of Biology fitness means how successful an organism has been at passing on its genes. The more likely that an individual is able to survive and live longer to reproduce, the higher is the fitness of that individual.

Answer 2

Biological fitness is the ability of the individual to contribute to the gene pool of the next generation. Hope this helps :)

Answer 3

Leaves more viable offspring than other of its species