Etymology Dictionary

CAP,  a covering for the head; a cover.  (Low Lat.)   In very early use.   A.S. cæppe, as a gloss to Low Lat. planeta, a chasuble; Ælfric's Glossary, Nomina Vasorum.—Low Lat. cappa, a cape, a cope; see capparius in Ducange.   [The words cap, cape, cope were all the same originally.]   This Low Lat. cappa, a cape, hooded cloak, occurs in a document of the year 660 (Diez); and is spelt capa by Isidore of Seville, 19. 31. 3, who says:  'Capa, quia quasi totum capiat hominem; capitis ornamentum.'   ¶ The remoter origin is disputed; Diez remarks that it is difficult to obtain the form capa from Lat. caput; and perhaps the derivation from Lat. capere, to contain, suggested by Isidore, may be right in this instance; though his guesses are mostly valueless.   This would explain its indifferent application in the senses of cap and cape; besides which, cape would appear to be the older and more usual meaning.   So Burguy.   See Cape, Cope.