- clearTransparent in colour.
- clarionA medieval brass instrument chiefly used as a battle signal; related to the trumpet, it had a narrow, straight pipe and a high-pitched, piercing sound.
- clarinetA woodwind musical instrument that has a distinctive liquid tone whose characteristics vary among its three registers: chalumeau (low), clarion (medium), and altissimo (high).
- ClermontA commune in Oise department, Hauts-de-France, France.
- claribellaAn organ stop with a soft, fluty sound.
- clarichordAn old musical instrument similar to a spinet, manichord or clavichord.
- ClaringboldA surname from Old French.
- glairEgg white, especially as used in various industrial preparations.