CONTAMINANT Meaning of CONTAMINANT in English con ‧ tam ‧ i ‧ nant /kənˈtæmənənt, kənˈtæmɪnənt/ BrE AmE noun [countable] formal a substance that makes something dirty:environmental contaminants Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012