- A mutagen is a chemical or physical phenomenon, such as ionizing radiation, that promotes errors in DNA replication. Exposure to a mutagen can produce DNA mutations that cause or contribute to diseases such as cancer.
Definition from: Talking Glossary of Genetic Terms from the National Human Genome Research Institute
- A substance (as a chemical or various radiations) that tends to increase the frequency or extent of mutation.
Definition from: Merriam-Webster's Medical Dictionary by Merriam-Webster Inc.
See also Understanding Medical Terminology.