It forms all or part of: cheese (n.2) "a big thing;" cue (n.1) "stage direction;" either; hidalgo; how; kickshaw; neither; neuter; qua; quality; quandary; quantity; quasar; quasi; quasi-; query; quib; quibble; quiddity; quidnunc; quip; quodlibet; quondam; quorum; quote; quotidian; quotient; ubi; ubiquity; what; when; whence; where; whether; which; whither; who; whoever; whom; whose; why.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kah "who, which;" Avestan ko, Hittite kuish "who;" Latin quis/quid "in what respect, to what extent; how, why," qua "where, which way," qui/quae/quod "who, which;" Lithuanian kas "who;" Old Church Slavonic kuto, Russian kto "who;" Old Irish ce, Welsh pwy "who;" Old English hwa, hwæt, hwær, etc.
How come? for "why?" is recorded from 1848 [Bartlett]. Emphatic phrase and how! is recorded from 1865. The formulation was common in book and article titles ("The National Debt, and How to Pay It"), but Pennsylvania writer Bayard Taylor, in whom it is first recorded, seems to have regarded it as a German or German-American expression.
1650s, "resembling a ladder," from Latin scalaris "of or pertaining to a ladder," from scalae (plural) "ladder, steps, flight of steps" (see scale (n.2)). The noun in the mathematical sense of "a real number" is from 1846, coined by Irish mathematician William R. Hamilton (1805-1865), who can explain why it is the correct word for that.
1818, "small house," from French maisonnette, diminutive of maison "house" (11c.), from Latin mansionem (see mansion). Meaning "a part of a building let separately" is by 1889.
You see, this is how it stands: I live in what the fellow who let the thing to me called a "maisonette"—goodness only knows why .... [Windsor Magazine, 1902]
pungent powder made from the root of an East Indian plant, 1530s, altered from Middle English turmeryte (early 15c.), which is of uncertain origin. "Middle English Compendium" compares Medieval Latin terra merita (16c.), French terre mérite (17c.), literally "worthy earth," though the reason why it would be called this is obscure. Klein suggests it might be a folk-etymology corruption of Arabic kurkum "curcuma, saffron."