xenobioticEnglishOxford Dictionary of Englishxenobiotic /ˌzɛnə(ʊ)bʌɪˈɒtɪk / ▸ adjective relating to or denoting a substance, typically a synthetic chemical, that is foreign to the body or to an ecological system: xenobiotic synthesis. ▸ (xenobiotics) noun a xenobiotic substance.