How can the answer be improved? Definition of pest 1 : an epidemic disease associated with high mortality specifically : plague 2 : something resembling a pest in destructiveness especially : a plant or animal detrimental to humans or human concerns (such as agriculture or livestock production) c.1400, "an angel who expells (people from a country)," from Late Latin exterminator, from Latin exterminatus, past participle stem of exterminare (see exterminate). As a substance for ridding a place of rats, etc., by 1848. As a person whose job it is to do this, by 1938. Used Occasionally. pest control is one of the 30000 most commonly used words in the Collins dictionary View usage for: All Years Last 10 years Last 50 years Last 100 years Last 300 years Nearby words of ‘pest control’ Times, Sunday Times (2016) It’s important for a pest controller to inspect the affected room after treatment, and to declare it officially clear of bugs. Times, Sunday Times (2016) BRITAIN’S most venomous spider has been added to a council’s pest control list in a city dubbed the false widow capital of the UK. Pest control is a huge category in the horticulture industry. Essentially, pest control encompasses everything a gardener does both to prevent pests from attacking their plants, and eradicate pest infestations once they occur.