CASTANET, noun An instrument of music formed of small concave shells of ivory or hard wood, shaped like spoons, placed together, fastened to the thumb and beat with the middle finger. This instrument is used by the Spaniards, Moors and Bohemians, as an accompaniment to their dances, sarabands and guitars.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI