chance (n.)youdaoicibaDictYouDict[chance 词源字典]
c. 1300, "something that takes place, what happens, an occurrence" (good or bad, but more often bad), from Old French cheance "accident, chance, fortune, luck, situation, the falling of dice" (12c., Modern French chance), from Vulgar Latin *cadentia "that which falls out," a term used in dice, from neuter plural of Latin cadens, present participle of cadere "to fall" (see case (n.1)).

In English frequently in plural, chances. The word's notions of "opportunity" and "randomness" are as old as the record of it in English and now all but crowd out the word's original notion of "mere occurrence." Main chance "thing of most importance" is from 1570s, bearing the older sense. The mathematical (and hence odds-making) sense is attested from 1778. To stand a chance (or not) is from 1796.

To take (one's) chances "accept what happens" (early 14c.) is from the old, neutral sense; to take a chance/take chances is originally (by 1814) "participate in a raffle or lottery or game;" extended sense of "take a risk" is by 1826.[chance etymology, chance origin, 英语词源]
haphazard (adj.)youdaoicibaDictYouDict
"characterized by randomness, chance, accidental," 1670s, from noun meaning "a chance, accident" (1570s), from hap (n.) "chance, luck" + hazard (n.) "risk, danger, peril." Related: Haphazardly.
random (adj.)youdaoicibaDictYouDict
"having no definite aim or purpose," 1650s, from at random (1560s), "at great speed" (thus, "carelessly, haphazardly"), alteration of Middle English noun randon "impetuosity, speed" (c. 1300), from Old French randon "rush, disorder, force, impetuosity," from randir "to run fast," from Frankish *rant "a running" or some other Germanic source, from Proto-Germanic *randa (cognates: Old High German rennen "to run," Old English rinnan "to flow, to run;" see run (v.)).

In 1980s U.S. college student slang it began to acquire a sense of "inferior, undesirable." (A 1980 William Safire column describes it as a college slang noun meaning "person who does not belong on our dormitory floor.") Random access in reference to computer memory is recorded from 1953. Related: Randomly; randomness.