severe Puritanical code said to have been enacted mid-17c. at the founding of New Haven and Connecticut colonies, 1781; of uncertain signification, perhaps from the notion of coldness, or from one of the figurative senses in blue (adj.1). Blue was the color adopted by 17c. Scottish Covenanters (in contradistinction to the royal red) and hence the color for a time acquired an association with strictness in morals or religion. Or perhaps connected to bluestocking in the sense of "puritanically plain or mean" (see bluestocking, which is a different application of the same term); the parliament of 1653 was derisively called the bluestocking parliament.
The assertion by some writers of the existence of the blue laws has no other basis than the adoption by the first authorities of the New Haven colony of the Scriptures as their code of law and government, and their strict application of Mosaic principles. [Century Dictionary]
Long, detailed lists of them often are given, but the original reference (in an anonymous history of Connecticut printed in London during the Revolution) says they were so-called by the neighboring colonies, "were never suffered to be printed," and then gives its own long list of them in quotations. The common explanation (dating to 1788) that they were written on blue paper is not now considered valid.
Old English denn "wild animal's lair, hollow place in the earth used by an animal for concealment, shelter, and security," from Proto-Germanic *danjan (source also of Middle Low German denne "lowland, wooded vale, den," Old English denu "valley," Old Frisian dene "down," Old High German tenni, German tenne "threshing floor," perhaps from a PIE word meaning "low ground").
Transferred to den-like places in human habitations in Middle English: "secret lurking place of thieves, place of retreat" (late 13c.); "apartment, private chamber" (late 14c.), but the modern use for "small room or lodging in which a man can seclude himself for work or leisure" [OED] is a modern development, originally colloquial, attested by 1771. By 1956, however, at least in U.S., the den had come to be a sort of family all-purpose room. In 19c. it also often had a bad sense, "a haunt, squalid place of retreat" (as in the set phrase den of iniquity for a brothel, etc.).
For, in truth, without a den or place of refuge, a man can achieve neither tranquility nor greatness. Jefferson wrote the Declaration of Independence in a quiet rooming house in Philadelphia. The soaring ideas that went into it evolved during hours of reading and contemplation in a secluded library. Had it been a study-TV-guest-family room, the United States might still be a colony. [The Kiplinger Magazine, September 1956]
c. 1300, gyrle "child, young person" (of either sex but most frequently of females), of unknown origin. One guess [OED] leans toward an unrecorded Old English *gyrele, from Proto-Germanic *gurwilon-, diminutive of *gurwjoz (apparently also represented by Low German gære "boy, girl," Norwegian dialectal gorre, Swedish dialectal gurre "small child," though the exact relationship, if any, between all these is obscure), from PIE *ghwrgh-, also found in Greek parthenos "virgin." But this involves some objectionable philology. Liberman (2008) writes:
Girl does not go back to any Old English or Old Germanic form. It is part of a large group of Germanic words whose root begins with a g or k and ends in r. The final consonant in girl is a diminutive suffix. The g-r words denote young animals, children, and all kinds of creatures considered immature, worthless, or past their prime.
Another candidate is Old English gierela "garment" (for possible sense evolution in this theory, compare brat). A former folk-etymology derivation from Latin garrulus "chattering, talkative" is now discarded. Like boy, lass, lad it is of more or less obscure origin. "Probably most of them arose as jocular transferred uses of words that had originally different meaning" [OED]. Specific meaning of "female child" is late 14c. Applied to "any young unmarried woman" since mid-15c. Meaning "sweetheart" is from 1640s. Old girl in reference to a woman of any age is recorded from 1826. Girl next door as a type of unflashy attractiveness is recorded by 1953 (the title of a 20th Century Fox film starring June Haver).
Doris [Day] was a big vocalist even before she hit the movies in 1948. There, as the latest movie colony "girl next door," sunny-faced Doris soon became a leading movie attraction as well as the world's top female recording star. "She's the girl next door, all right," said one Hollywood admirer. "Next door to the bank." [Life magazine, Dec. 22, 1958]
Girl Friday "resourceful young woman assistant" is from 1940, a reference to "Robinson Crusoe." Girl Scout is from 1909. For the usual Old English word, see maiden.
early 13c., "skin color, complexion," from Anglo-French culur, coulour, Old French color "color, complexion, appearance" (Modern French couleur), from Latin color "color of the skin; color in general, hue; appearance," from Old Latin colos, originally "a covering" (akin to celare "to hide, conceal"), from PIE root *kel- (1) "to cover, conceal, save." Old English words for "color" were hiw ("hue"), bleo. For sense evolution, compare Sanskrit varnah "covering, color," which is related to vrnoti "covers," and also see chroma.
Colour was the usual English spelling from 14c., from Anglo-French. Classical correction made color an alternative from 15c., and that spelling became established in the U.S. (see -or).
Meaning "a hue or tint, a visible color, the color of something" is from c. 1300. As "color as an inherent property of matter, that quality of a thing or appearance which is perceived by the eye alone," from late 14c. From early 14c. as "a coloring matter, pigment, dye." From mid-14c. as "kind, sort, variety, description." From late 14c. in figurative sense of "stylistic device, embellishment. From c. 1300 as "a reason or argument advanced by way of justifying, explaining, or excusing an action," hence "specious reason or argument, that which hides the real character of something" (late 14c.).
From c. 1300 as "distinctive mark of identification" (as of a badge or insignia or livery, later of a prize-fighter, horse-rider, etc.), originally in reference to a coat of arms. Hence figurative sense as in show one's (true) colors "reveal one's opinions or intentions;" compare colors.
In reference to "the hue of the darker (as distinguished from the 'white') varieties of mankind" [OED], attested from 1792, in people of colour, in translations from French in reference to the French colony of Saint-Domingue (modern Haiti) and there meaning "mulattoes."
In reference to musical tone from 1590s. Color-scheme is from 1860. Color-coded is by 1943, in reference to wiring in radios and military aircraft. Color-line in reference to social and legal discrimination by race in the U.S. is from 1875, originally referring to Southern whites voting in unity and taking back control of state governments during Reconstruction (it had been called white line about a year earlier, and with more accuracy).