plural of knee-cap (alternative spelling of kneecaps).

A market-based approach to control pollution by providing economic incentives for achieving reductions in emissions, participating companies being assigned an emissions quota that can be traded with others if not used.

Any of various originally military caps intended for undress or working use.

plural of mob cap

plural of flat cap

plural of ice cap

plural of cradle cap

plural of Caps Lock

plural of bouffant cap

plural of polar cap