1. evolutionary. Some property of an organism caused by natural selection acting on the genotype, improving the fitness of an organism. This is a long term process.

2. physiological. A physiological change in an organism, resulting from exposure to certain environmental conditions, allowing it to respond more effectively to them (e.g. tanning of the skin in sunshine).

3. sensory. A short term change in excitability of a sense organ through continuous stimulation.

Alternative forms for adaptation : adaptations, adapted, adaptive.