Carcinogen (noun)

1. A substance or agent that is capable of causing cancer in living tissue.
2. A substance or agent that is capable of promoting cancer formation.

Origin:

From the greek word karkinos ("crab") + -gen ("producer of"), because cancers were thought to resemble crabs.

Examples:

1. Smoking is a known carcinogen, increasing the risk of lung cancer.
2. Exposure to certain chemicals at work may increase the risk of developing cancer due to their carcinogenic properties.
3. According to research, prolonged exposure to UV radiation is a carcinogen that can cause skin cancer.
4. The Environmental Protection Agency lists certain pesticides as carcinogens.
5. Many processed meats have been classified as carcinogens by the World Health Organization.