We found 21 dictionaries that define the word heavy metals:

General (10 matching dictionaries)

1. heavy metals: Merriam-Webster
2. heavy metals: Collins English Dictionary
3. heavy metals: Vocabulary.com
4. heavy metals: Wordnik
5. heavy metals: Cambridge Advanced Learner's Dictionary
6. heavy metals: Wiktionary
7. Heavy metals: Dictionary.com
8. Heavy Metals, Heavy metals: Wikipedia, the Free Encyclopedia
9. heavy metals: FreeDictionary.org
10. Heavy metals: TheFreeDictionary.com

Business (3 matching dictionaries)

11. Heavy metals: Energy Dictionary
12. Heavy metals: Legal dictionary
13. Heavy metals: Financial dictionary

Computing (1 matching dictionary)

14. Heavy metals: Encyclopedia

Medicine (4 matching dictionaries)

15. Medical Dictionary (No longer online)
16. Heavy metals: Merck Manuals
17. online medical dictionary (No longer online)
18. Metals, heavy, heavy metals: Medical dictionary

Science (1 matching dictionary)

19. heavy metals: Evolution Glossary

Tech (2 matching dictionaries)

20. AUTOMOTIVE TERMS (No longer online)
21. Lake and Water Word Glossary (No longer online)

(Note: See heavy_metal as well.)

Definitions from Wikipedia (Heavy metals) ▸ noun:  a controversial and ambiguous term for metallic elements with relatively high densities, atomic weights, or atomic numbers. ▸ Words similar to heavy metals ▸ Usage examples for heavy metals ▸ Idioms related to heavy metals ▸ Wikipedia articles (New!) ▸ Words that often appear near heavy metals ▸ Rhymes of heavy metals ▸ Invented words related to heavy metals