aptitude (n.) Look up aptitude at Dictionary.com
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.