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1540s, "abrasion, a scraping," from Latin attritionem (nominative attritio), literally "a rubbing against," noun of action from past participle stem of atterere "to wear, rub away," figuratively "to destroy, waste," from ad- "to" (see ad-) + terere "to rub" (see throw (v.)). The earliest sense in English is from Scholastic theology (late 14c.), "sorrow for sin merely out of fear of punishment," a minor irritation, and thus less than contrition. The sense of "wearing down of military strength" is a World War I coinage (1914). Figurative use by 1930.
attrition at·tri·tion (ə-trĭsh'ən)
A wearing away by friction or rubbing, such as the loss of tooth structure caused by abrasive foods or grinding of the teeth.