"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.
Entries linking to haphazard
hap n.
c. 1200, "chance, a person's luck, fortune, fate;" also "unforeseen occurrence," from Old Norse happ "chance, good luck," from Proto-Germanic *hap- (source of Old English gehæp "convenient, fit"), from PIE *kob- "to suit, fit, succeed" (source also of Sanskrit kob "good omen; congratulations, good wishes," Old Irish cob "victory," Norwegian heppa "lucky, favorable, propitious," Old Church Slavonic kobu "fate, foreboding, omen"). Meaning "good fortune" in English is from early 13c. Old Norse seems to have had the word only in positive senses.
hazard n.
c. 1300, name of a game at dice, from Old French hasard, hasart "game of chance played with dice," also "a throw of six in dice" (12c.), of uncertain origin. Possibly from Spanish azar "an unfortunate card or throw at dice," which is said to be from Arabic az-zahr (for al-zahr) "the die." But this is doubtful because of the absence of zahr in classical Arabic dictionaries. Klein suggests Arabic yasara "he played at dice;" Arabic -s- regularly becomes Spanish -z-. The -d was added in French through confusion with the native suffix -ard. Sense evolved in French to "chances in gambling," then "chances in life." In English, sense of "chance of loss or harm, risk" first recorded 1540s.
half-assed adj.
"ineffectual," 1932; "Dictionary of American Slang" suggests it is perhaps a humorous mispronunciation of haphazard. Compare half-hearted.