rocker

1 a :  either of two curving pieces of wood or metal on which an object (as a cradle) rocks b :  any of various objects (as a rocking chair or an infant's toy having a seat placed between side pieces) that rock on rockers c :  any of various objects in the form of a rocker or with parts resembling a rocker (as a skate with a curved blade) d (1) :  any of the curved stripes at the lower part of a chevron worn by a noncommissioned officer above the rank of sergeant (2) :  the curved stripe at the upper part of a chevron worn by a chief petty officer

2 :  any of various devices that work with a rocking motion

3 :  a rock performer, song, or enthusiast