xenobioticPronunciation: /ˌzɛnə(ʊ)bʌɪˈɒtɪk/Definition of xenobiotic adjective relating to or denoting a substance, typically a synthetic chemical, that is foreign to the body or to an ecological system: xenobiotic synthesis noun (usually xenobiotics) a xenobiotic substance. xenobiotic in other Oxford dictionaries Definition of xenobiotic in the US English dictionary