Cap  —n. 1 a soft brimless hat, usu. With a peak. B head-covering worn in a particular profession. C cap as a sign of membership of a sports team. D mortarboard. 2 a cover like a cap (kneecap). B top for a bottle, jar, pen, camera lens, etc. 3 = *dutch cap. 4 = *percussion cap. 5 dental crown. —v. (-pp-) 1 a put a cap on. B cover the top or end of. C set a limit to (charge-capping). 2 award a sports cap to. 3 form the top of. 4 surpass, excel.  cap in hand humbly. If the cap fits (of a remark) if it applies to you, so be it. To cap it all after everything else. [latin cappa]