rocker

noun

• 1a person who performs, dances to, or enjoys rock music, especially of a particular type:a punk rocker
• a rock song.

• 2a thing that rocks, in particular.
• a rocking chair.
• a rocking device forming part of a mechanism, especially one for controlling the positions of brushes in a generator.

• 3a curved bar or similar support on which something such as a chair or cradle can rock.

• 4the amount of curvature in the longitudinal contour of a boat or surfboard.

• 5any of the curved stripes below the chevron of a noncommissioned officer above the rank of sergeant.
• the curved strip above the chevron of a chief petty officer.