MASTIFF Meaning of MASTIFF in English [ 'mastɪf , 'mα:- ]■ noun a dog of a large, strong breed with drooping ears and pendulous lips.OriginME: from OFr. mastin , based on L. mansuetus 'tame'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004