A percussion instrument (idiophone) of Spanish origin, consisting of a pair of concave shells joined on one edge by a string, held in the hand and used to produce clicking sounds; any hand-held percussion idiophone that can be played with the fingers, such as bones or spoons.

(music, chiefly in the plural) A single handheld percussion instrument consisting of a pair of concave shells or shell-shaped parts joined on one edge by string.

One who plays the castanet.

plural of castanetist