Yes, rocker is a Scrabble word!

Noun

1. An attendant who rocks a child in a cradle

2. A performer or composer or fan of rock music

3. A teenager or young adult in the 1960s who wore leather jackets and rode motorcycles

4. A chair mounted on rockers

5. A trough that can be rocked back and forth; used by gold miners to shake auriferous earth in water in order to separate the gold

6. An ice skate with a curved blade

7. A curved support that permits the supported object to rock to and fro