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dangerous (adj.): early 13c., "difficult, arrogant, severe" (the opposite of affable), from Anglo-French dangerous, Old French dangeros (12c., Modern French dangereux), from danger (see danger).

In Chaucer, it means "hard to please, reluctant to give;" sense of "full of danger, risky" is from late 15c. Other words used in this sense included dangersome (1560s), dangerful (1540s). Related: Dangerously.
hang (v.): a fusion of Old English hon "suspend" (transitive, class VII strong verb; past tense heng, past participle hangen), and Old English hangian "be suspended" (intransitive, weak, past tense hangode); also probably influenced by Old Norse hengja "suspend," and hanga "be suspended." All from Proto-Germanic *hanhan (transitive), *hangen (intransitive) "to hang" (cognates: Old Frisian hangia, Dutch hangen, German hängen), from PIE *konk- "to hang" (cognates: Gothic hahan, Hittite gang- "to hang," Sanskrit sankate "wavers," Latin cunctari "to delay;" see also second element in Stonehenge).

As a method of execution, in late Old English (but originally specifically of crucifixion). Meaning "to come to a standstill" (especially in hung jury) is from 1848, American English. Hung emerged as past participle 16c. in northern England dialect, and hanged endured only in legal language (which tends to be conservative) in reference to capital punishment and in metaphors extended from it (I'll be hanged).

Teen slang sense of "spend time" first recorded 1951; hang around "idle, loiter" is from 1828, American English; also compare hang out. To hang back "be reluctant to proceed" is from 1580s; phrase hang an arse "hesitate, hold back" is from 1590s. Verbal phrase hang fire (1781) originally was used of guns that were slow in communicating the fire through the vent to the charge. To let it all hang out "be relaxed and uninhibited" is from 1967.
recusant (adj.): "obstinate in refusal," 1550s, from Latin recusantem (nominative recusans) "refusing to obey," present participle of recusare "make an objection against; decline, refuse, reject; be reluctant to" (see recuse). The noun meaning "one obstinate in refusing" is from 1610s.
recuse (v.): late 14c., "to reject another's authority as prejudiced," from Old French recuser (13c.), from Latin recusare "make an objection against; decline, refuse, reject; be reluctant to," from re- (see re-) + causa (see cause (n.)). Specifically, in law, "reject or challenge (a judge or juror) as disqualified to act." The word now is used mostly reflectively. Related: Recused; recusing.