v. & n.
v. 1 tr. move gently to and fro in or as if in a cradle; set or maintain such motion (rock him to sleep; the ship was rocked by the waves). 2 intr. be or continue in such motion (sat rocking in his chair; the ship was rocking on the waves). 3 a intr. sway from side to side; shake, oscillate, reel (the house rocks). b tr. cause to do this (an earthquake rocked the house). 4 tr. distress, perturb. 5 intr. dance to or play rock music.
n. 1 a rocking movement (gave the chair a rock). 2 a spell of rocking (had a rock in his chair). 3 a = rock and roll. b any of a variety of types of modern popular music with a rocking or swinging beat, derived from rock and roll. rock and (or rock 'n') roll a type of popular dance-music originating in the 1950s, characterized by a heavy beat and simple melodies, often with a blues element. rock and (or rock 'n') roller a devotee of rock and roll. rock the boat colloq. disturb the equilibrium of a situation. rocking-chair a chair mounted on rockers or springs for gently rocking in. rocking-horse a model of a horse on rockers or springs for a child to rock on. rocking-stone a poised boulder easily rocked. rock-shaft a shaft that oscillates about an axis without making complete revolutions.
[ OE roccian, prob. f. Gmc ]