(engineering) A closed nut having a dome-like cap over the back, protruding part of the engaged screw or bolt.

(medicine, pathology) A form of seborrheic dermatitis that occurs on the scalps of infants, causing scaly, flaky, itchy, red skin.

Alternative spelling of cap gun

A knitted woolen cap, often with a tassel.

Alternative spelling of watch cap

A knitted cap, such as the one worn by a seaman when on watch.

A cap with a rounded crown and a curved, stiffened bill at the front.

(US) A cap that is not elasticated or adjustable at the back.

A cap, usually brightly coloured with bells and tassels, as worn by a court jester or fool.

A permanent expanse of ice encompassing a large geographical area, e.g. in Earth's polar zones or at high elevation. [from 19th c.]