"curl or lock of hair over the forehead," by 1890, originally a style among soldiers, a word of unknown origin. Perhaps connected with quiff "a puff or whiff of tobacco smoke" (1831, originally Southern U.S.), which is held to be a variant of whiff (n.).
1708, "curl-like fringe or tuft," from Latin cirrus "a lock of hair, tendril, curl, ringlet of hair; the fringe of a garment." In meteorology, in reference to light, fleecy clouds, attested from 1803; so called from fancied resemblance of shape.
late 14c., combinacyoun, "act of uniting (two things) in a whole; state of being so united," from Old French combination (14c., Modern French combinaison), from Late Latin combinationem (nominative combinatio) "a joining two by two," noun of action from past participle stem of combinare "to unite, yoke together," from Latin com "with, together" (see com-) + bini "two by two," adverb from bi- "twice" (from PIE root *dwo- "two").
Sense of "a whole formed by uniting" is from 1530s; specific sense of "union or association of persons for the attainment of some common end" is from 1570s. Meaning "series of moves required to open a combination lock" is from 1880; combination lock, one requiring a certain combination of moves to open it, is from 1851. Related: Combinational.
"informal session of folk musicians," 1940, American English, earlier "a gadget" (1927), of unknown origin, perhaps a nonsense word.
Another device used by the professional car thief, and one recently developed to perfection, according to a large Chicago lock-testing laboratory, is a "hootenanny," so-called by the criminals using it. [Popular Mechanics, February 1931]
1540s, "one who detects," from Latin detector "uncoverer, revealer," agent noun from detectus, past participle of detegere "to uncover, expose," figuratively "discover, reveal, disclose" (see detect). From 1833 as "instrument or device for indicating the presence or state of a thing," originally an arrangement in a lock supposed to indicate attempts to tamper with it.