probability (n.)youdaoicibaDictYouDict[probability 词源字典]
mid-15c., "quality of being probable," from Old French probabilite (14c.) and directly from Latin probabilitatem (nominative probabilitas) "credibility, probability," from probabilis (see probable). Meaning "something likely to be true" is from 1570s; mathematical sense is from 1718.[probability etymology, probability origin, 英语词源]