The shaken instrument — a handheld frame of loose rods that sounds when moved. Latin, from Greek σεῖστρον, "that which is shaken"; carried in the old rites to move the air of a room and change what stands in it. Rhythm as a thing done to a space, not merely heard in one.
Greek seistron (that which is shaken), from seiein (to shake), via Latin sistrum; carried in old rites to move the air of a room and change what stood in it.
The shaken instrument whose sound is meant to move the air of a room and change what stands in it — rhythm done to a space, not merely heard inside one.