propensity (n.)youdaoicibaDictYouDict[propensity 词源字典]
1560s, "disposition to favor," with -ty + obsolete adjective propense "inclined, prone" (1520s), from Latin propensus, past participle of propendere "incline to, hang forward, hang down, weigh over," from pro- "forward" (see pro-) + pendere "hang" (see pendant).[propensity etymology, propensity origin, 英语词源]