A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. Wikipedia

Chemical substance or microorganism used against a harmful organism Wikidata

A diverse group of poisonous substance including preservatives, insecticides, disinfectants and pesticides used for the control of organisms that are harmful to human or animal health or that cause damage to natural or manufactured products. OmegaWiki

Any action or substance that can destroy living organisms. Wiktionary

Any substance that can destroy living organisms. Wiktionary (translation)