A small coin formerly used in medieval England worth four pence; also a grain like barley or oats used in cooking and porridge.
From Dutch 'groot' (great/large), because a groat was originally a large coin. Later, the term applied to hulled grains that look like small pellets, possibly from the same root suggesting 'granular' or 'grainy.'
Groats were so common in medieval times that 'not worth a groat' became an expression meaning something worthless—Shakespeare used it in his plays, and the term survived hundreds of years even after the actual coins disappeared.
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