Etymology: Middle English cappe, from Old English cæppe, from Late Latin cappa head covering, cloak
Date: before 12th century
1 a: a head covering especially with a visor and no brim b: a distinctive head covering emblematic of a position or office: as (1): a cardinal's biretta (2):mortarboard 2: a natural cover or top: as a: an overlying rock layer that is usually hard to penetrate b (1):pileus(2):calyptrac: the top of a bird's head or a patch of distinctively colored feathers in this area 3 a: something that serves as a cover or protection especially for a tip, knob, or end <a bottle cap>b: a fitting for closing the end of a tube (as a water pipe or electric conduit) cBritish:cervical capd: an artificial crown for a tooth 4: an overlaying or covering structure 5: a paper or metal container holding an explosive charge (as for a toy pistol) 6: an upper limit (as on expenditures) :ceiling 7: the symbol ∩ indicating the intersection of two sets — compare cup 9 8: a cluster of molecules or chemical groups bound to one end or a region of a cell, virus, or molecule
— cap in hand: in a respectful, humble, or sometimes fearful manner