castanet: [17] Castanets were originally named in Spanish from their resemblance to the shells of chestnuts, Spanish castañeta being a diminutive form of castaña ‘chestnut’, from Latin castanea (itself the ultimate source of English chestnut). Another name for them in 17th-century English was knackers: ‘Castinettas: knackers of the form of chestnuts, used to this day by the Spaniards in their dances’, Robert Stapylton, Juvenal’s sixteen satires 1647. => chestnut
usually castanets, 1640s, from French castagnette or directly from Spanish castañeta diminutive of castaña "chestnut," from Latin castanea (see chestnut).
