cornet UK /ˈkɔːnɪt/US /kɔɹˈnɛt/noun 10forms 1 noun10 •A musical instrument of the brass family, slightly smaller than a trumpet, usually in the musical key of B-flat. •An ice cream cone (the shell itself). •(UK, old-fashioned) An ice cream cone (the unit comprising the shell and the ice cream). •A piece of paper twisted to be used as a container. •(historical) The fifth commissioned officer in a cavalry troop, who carried the colours (equivalent to the ensign in infantry).No general would have sent a mere cornet in command of five hundred horse: Fairfax despatched a colonel to take charge as soon as he heard what had happened. — 1972 •A kind of organ stop. •The white headdress worn by the Sisters of Charity. •A hollow horn-like growth. •(no longer used) A troop of cavalry; so called from its being accompanied by a cornet player.They discerned a body of five cornets of horse very full, standing in very good order to receive them. — 1702 •(no longer used) The standard flown by a cavalry troop. formscornets