From Longman Dictionary of Contemporary Englishbuckwheatbuck‧wheat /ˈbʌkwiːt/ noun [uncountable] DFa type of small grain used as food for chickens, and for making flour
Examples from the Corpus
buckwheat• Traditionally, rain-fed terraces are constructed on steeper slopes in the Middle Mountains for the production of maize, millet and buckwheat.• For wholefood enthusiasts, I would recommend buckwheat pasta rather than wholemeal, which I think is rather dull in flavour and texture.• The talented chef uses buckwheat soba noodles effectively.Origin buckwheat (1500-1600) Middle Dutch boecweit, from boec “beech” + weit “wheat”; because the grains are the same shape as beech-tree seeds 