heavy metal

Short definition from Wiktionary

Noun

1. 1
   Any metal that has a specific gravity greater than about 5, especially one, such as lead, that is poisonous and may be a hazard in the environment. (There are many different definitions of what counts as a heavy metal; see Heavy metals for a discussion.)
2. 2
   A genre descended from rock music, characterized by the use of emphatic drumbeats, highly amplified distortion, and overall loudness; often featuring extended instrumental solos and powerful vocals.
3. 3
   A genre descended from rock music, characterized by the use of emphatic drumbeats, highly amplified distortion, and overall loudness; often featuring extended instrumental solos and powerful vocals: The first form of metal music, which arose in the late 1960s and the 1970s, and is closer to the rock music of the time than most other subgenres of metal.
4. 4
   guns or shot of large size.
5. 5
   Great influence or power.