"violent muscular spasms," 1817, from Modern Latin, from Greek klonos "turmoil, any violent motion; confusion, tumult, press of battle," from PIE *kel- "to drive, set in motion." Related: Clonic; clonicity.
clonus clo·nus (klō'nəs)
n. pl. clo·nus·es
A form of movement marked by contractions and relaxations of a muscle, occurring in rapid succession, after forcible extension or flexion of a part. Also called clonospasm.