Riot control agent. After September 11, 2001, the _____________ was established to provide a framework that provides a comprehensive national approach, applicable at all jurisdictional levels and across functional disciplines.
noun, plural: chemicals. (1) A substance made up of chemical elements or produced from a chemical process. (2) A drug, especially illicit or addictive drug. adjective. Of, relating to, or pertaining to, chemistry or a chemical substance.
Top Definition. Chemical. 1. Chemicals are pure substances that make up the universe. They can be benign (harmless) such as trihydrogenoxide or malevolent (harmful) such as dihydrogenoxide. 2. Pertaining to chemistry, the study of chemicals. Your food is full of chemicals that might kill you.