Fitness may mean: The state of being physically active on a regular basis to maintain good physical condition...
* Physical fitness, a general state of good health, usually as a result of exercise and nutrition
* Cardiorespiratory fitness
* Fitness approximation, model of the fitness function to choose smart search steps in Evolutionary algorithms including GA.
* Fitness and figure competition, a form of physique training, related to bodybuilding.
* In mathematics and computer science, the degree to which a given solution is optimized; see optimization (mathematics) or Fitness function
* Fitness (biology), an individual's ability to propagate its genes.
* FitNesse, a web server, a wiki, and a software testing tool.
* Fitness (magazine), a women's magazine, focusing on health and exercise.