A xenobiotic (Greek, xenos 'foreign'; bios 'life') is a compound that is foreign to a living organism. Principal xenobiotics include: drugs; carcinogens; and various compounds that have been introduced into the environment by artificial means.
PAC, 1997, 69, 1251. (Glossary of terms used in bioinorganic chemistry (IUPAC Recommendations 1997)) on page 1303 [Terms] [Paper]
This definition replaces an earlier definition of xenobiotics.