- The definition of a pesticide is a chemical or other substance used to kill unwanted insects or weeds.
A spray used to kill ants is an example of apesticide.
any chemical used for killing insects, weeds, etc.
Origin of pesticide; from pest + -cide
A substance or agent used to kill pests, such as unwanted or harmful insects, rodents, or weeds.
pest + -i- + -cide