FROCK, originally a long, loose gown with broad sleeves, more especially that worn by members of the religious orders. The word is derived from the O. Fr. froc, of somewhat obscure origin; in medieval Lat. froccus appears also as floccus, which, if it is the original, as Du Cange suggests (literula mutata), would connect the word with "flock" (q.v.), properly a tuft of wool. Another suggestion refers the word to the German Rock, a coat (cf. "rochet"), which in some rare instances is found as hrock. The formal stripping off of the frock became part of the ceremony of degradation or deprivation in the case of a condemned monk; hence the expression "to unfrock" (med. Lat. defrocare, Fr. défroquer) used of the degradation of monks and of priests from holy orders. In the middle ages "frock" was also used of a long loose coat worn by men and of a coat of mail, the "frock of mail." In something of this sense the word survived into the 19th century for a coat with long skirts, now called the "frock coat." The word in now chiefly used in English for a child's or young girl's dress, of body and skirt, but is frequently used of a woman's dress. Du Cange (Glossarium, s.v. flocus) quotes an early use of the word for a woman's garment (Miracula S. Udalrici, ap. Mabillon, Acta Sanctorum Benedict, saec. v. p. 466). Here a woman, possessed of a devil, is cured, and sends her garments to the tomb of the saint, and a dalmatic is ordered to be made out of the flocus or frocus. "Frock" also appears in the "smock frock," once the typical outer garment of the English peasant. It consists of a loose shirt of linen or other material, worn over the other clothes and hanging to about the knee; its characteristic feature is the "smocking," a puckered honeycomb stitching round the neck and shoulders.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)