Aptitude

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late Middle English: via Old French from late Latin aptitudo, from aptus (see apt).

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Middle French aptitude, from Medieval Latin aptitudo, from Latin aptus(“apt, fit”). Doublet of attitude.

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aptitude (n.)

early 15c., "tendency, likelihood," from Late Latin aptitudo (genitive aptitudinis) "fitness," noun of quality from Latin aptus "joined, fitted" (see apt). Meaning "natural capacity to learn" is 1540s; that of "state or quality of being fit (for a purpose or position)" is from 1640s. Related: Aptitudinal. A doublet of attitude.