nouninformal, slang North American
1A person who studies or collects insects or other bugs; an entomologist. Often somewhat depreciative.
2A substance or device used to deter, control, or kill insects and other bugs; an insect repellent; an insecticide.
Occasionally also: a person who eradicates insects and other bugs from a building, etc.
3(usually depreciative). A person who studies or investigates bacteria, viruses, etc., or the diseases caused by them; a microbiologist or epidemiologist.
4A person (especially a homosexual man) who actively seeks infection with the HIV virus through unprotected sex with HIV-positive partners.
Late 19th century; earliest use found in Makio. From bug + chaser.