Old English dohtor, from Proto-Germanic *dochter, earlier *dhukter (cf. Old Saxon dohtar, Old Norse dottir, Old Frisian and Dutch dochter, German Tochter, Gothic dauhtar), from PIE *dhugheter (cf. Sanskrit duhitar-, Avestan dugeda-, Armenian dustr, Old Church Slavonic dušti, Lithuanian dukte, Greek thygater). The common Indo-European word, lost in Celtic and Latin (Latin filia "daughter" is fem. of filius "son"). The modern spelling evolved 16c. in southern England. Daughter-in-law is attested from late 14c.
This word, besides its natural and proper sense, is used to designate, (1.) A niece or any female descendant (Gen. 20:12; 24:48; 28:6). (2.) Women as natives of a place, or as professing the religion of a place; as, "the daughters of Zion" (Isa. 3:16), "daughters of the Philistines" (2 Sam. 1:20). (3.) Small towns and villages lying around a city are its "daughters," as related to the metropolis or mother city. Tyre is in this sense called the daughter of Sidon (Isa. 23:12). (4.) The people of Jerusalem are spoken of as "the daughters of Zion" (Isa. 37:22). (5.) The daughters of a tree are its boughs (Gen. 49:22). (6.) The "daughters of music" (Eccl. 12:4) are singing women.