Meaning of “rock” - Learner’s Dictionary

rock

noun uk us /rɒk/
SUBSTANCE [ U ]

B1 the hard, natural substance that forms part of the Earth's surface:

a layer of volcanic rock
LARGE PIECE [ C ]

B1 a large piece of rock or stone:

Huge waves were crashing against the rocks.
MUSIC [ U ]

A2 loud, modern music with a strong beat, often played with electric guitars and drums:

hard/soft rock
rock music
a rock band/singer

(Definition of “rock noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)