maiden (n.)

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.

c. 1200 (late 12c. in place names and surnames), "an unmarried woman (usually young); the Virgin Mary;" shortening of maiden (n.). Like that word, used in Middle English of unmarried men as well as women (as in maiden-man, c. 1200, which was used of both sexes, reflecting also the generic use of man).

From c. 1300 as "a virgin," also as "maidservant, female attendant, lady in waiting." By c. 1500 this had yielded the humbler sense of "female servant or attendant charged with domestic duties." Often with a qualifying word (housemaid, chambermaid, etc.); maid of all work "female servant who performs general housework" is by 1790.

Her Mamma was a famous Fryer of Fishes,

Squeezer of Mops, Washer of Dishes,

From tossing of Pancakes would not Shirk,

In English plain, a Maid of all Work.

But don't mistake me, by Divinity,

When I mention Maid, I don't mean Virginity 

[from "Countess of Fame and her Trumpeter," 1793]

In reference to Joan of Arc, attested from 1540s (French la Pucelle). Maid Marian, the Queen of the May in the morris dances, also one of Robin Hood's companions, is recorded by 1520s, perhaps from French, where Robin et Marian have been stock names for country lovers since 13c. Maid of Honor (1580s) originally was "unmarried lady of noble birth who attends a queen or princess;" meaning "principal bridesmaid" is attested from 1895. Maydelond (translating Latin terra feminarum) was "the land of the Amazons."