murrainPronunciation: /ˈmʌrɪn/Definition of murrain noun 1 [mass noun] redwater fever or a similar infectious disease affecting cattle or other animals. 2 archaic a plague, epidemic, or crop blight. the potato blight during the Irish famine in the mid 19th century. Origin: late Middle English: from Old French morine, based on Latin mori 'to die'murrain in other Oxford dictionaries Definition of murrain in the US English dictionary