Longman Dictionary English From Longman Dictionary of Contemporary EnglishRelated topics: Nutritionthiaminthi‧am‧in, thiamine /ˈθaɪəmiːn, -mɪn/ noun [uncountable] DFNa natural chemical in some foods, that you need in order to prevent particular illnessesOrigin thiamin (1900-2000) Greek theion “sulfur” + English -amin (as in vitamin) ldoceonline.com