heavy metal 
noun
1A metal of relatively high density, or of high relative atomic weight: heavy metals are taken up by plants [as modifier]: heavy metal contamination...
- For example, tobacco plants can absorb heavy metals, mercury, copper, and lead.
- They also evaluated its ability to stem soil and groundwater contamination by nutrients and heavy metals.
- For shallow soil contamination, heavy metals can be stabilized in place.
2 [mass noun] A type of highly amplified harsh-sounding rock music with a strong beat, characteristically using violent or fantastic imagery: a carload of adolescents playing heavy metal with their windows open [as modifier]: a heavy metal band heavy metal fans...
- Before I had went to bed last night he was blasting some heavy metal rock music.
- This means hardcore fans of British heavy metal can finally get some respect.
- They have been smart enough to roll with the changes while staying true to their hard rock and heavy metal tunes.