diminish [LME] This is a medieval English blend of two obsolete words that share its meaning, ‘to lessen’: diminue and minish. Both ultimately go back to Latin minutus ‘small’, the source of *minute in the same sense. In economics the law of diminishing returns draws attention to the point at which profits are less than the amount of money invested. It originated in the first half of the 19th century with reference to profits from agriculture.