an attendant who rocks a child in a cradle
"The tired rocker gently swayed the baby in the wooden cradle until it fell asleep."
a performer or composer or fan of rock music
"The local rocker was thrilled to see his favorite band perform at the festival last night."
a teenager or young adult in the 1960s who wore leather jackets and rode motorcycles
"The local rocker customized his motorcycle and often met at the garage to listen to new music."
a chair mounted on rockers
"The old rocking chair creaked softly as her grandmother pushed it back and forth to sing a lullaby."
an ice skate with a curved blade
"The figure skater glided effortlessly across the ice on her sharp rocker blades."
a curved support that permits the supported object to rock to and fro
"The rocking chair rests on two metal rocker supports that allow it to sway gently back and forth."
A curved piece of wood attached to the bottom of a rocking chair or cradle that enables it to rock back and forth.
"The smooth wooden rocker on her grandfather's chair glided effortlessly over the floorboards as she gently rocked him to sleep."
In plain English: A rocker is someone who likes to rock out by listening to loud music and moving their body rhythmically, often wearing clothes with leather or studs.
"The old rocker creaked gently when my grandfather sat down to read his newspaper."
Usage: Do not confuse this noun with the verb "to rocker," which is nonstandard; use "rock" instead when describing the action. In casual speech, people sometimes refer to the entire chair as a rocker, though technically only the curved base holds that name.
The word rocker comes from the Middle English term rokker, which was formed by adding a suffix meaning "one who does something" to an older form of the verb for moving back and forth. This construction created a noun describing a person or object that rocks, preserving the original sense of the action into modern English.