early 15c. (implied in adapted) "to fit (something, for some purpose)," from Old French adapter (14c.), from Latin adaptare "adjust, fit to," from ad "to" (see ad-) + aptare "to join," from aptus "fitted" (see apt). Intransitive meaning "to undergo modification so as to fit new circumstances" is from 1956. Related: Adapting.
word-forming element expressing ability, fitness, or capacity, from Latin -abilitas, forming nouns from adjectives ending in -abilis (see -able). Not etymologically related to ability, though popularly connected with it.
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Harper, D. (n.d.). Etymology of adaptability. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/adaptability