Adaptation

From EvoWiki

An adaptation refers to any heritable aspect of an organism's phenotype that increases (or increased) its survival and reproductive success; that is, a phenotype that was selected for.

"Adaptation" is a noun, and not a verb, though many people use it as a synonym for the processes of evolution (variation, selection etc). This is probabaly harmless, but the use of the word as a verb may incorrectly suggest that the processes that produce an adaptation are teleological, that is, they are purposefully producing the adaptation. In reality variation is random, while selection is a blind non-teleological process.