early 15c., attricioun, "a breaking;" 1540s, "abrasion, scraping, the rubbing of one thing against another," 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 assimilated form of ad "to" (see ad-) + terere "to rub" (from PIE root *tere- (1) "to rub, turn").
The earliest sense in English is from Scholastic theology (late 14c.): "sorrow for sin merely out of fear of punishment or a sense of shame," an imperfect condition, less than contrition or repentance. The sense of "wearing down of military strength" is from World War I (1914). Figurative use of that is by 1930.
"wear down or grind down by means of sustained actions," 1956, U.S. Air Force back-formation from attrition in the military sense. It attained currency during the Vietnam War. Related: Attritted; attritting.
"worn down, worn by rubbing or friction" (obsolete), 1620s, from Latin attritus, past participle of atterere "to wear, rub away" (see attrition). Related: Attriteness.
*terə-, Proto-Indo-European root meaning "to rub, turn," with derivatives referring to twisting, also to boring, drilling, piercing; and to the rubbing of cereal grain to remove the husks, and thus to threshing.
It forms all or part of: atresia; attorn; attorney; attrition; contour; contrite; detour; detriment; diatribe; drill (v.) "bore a hole;" lithotripsy; return; septentrion; thrash; thread; thresh; throw; threshold; trauma; trepan; tribadism; tribology; tribulation; trite; triticale; triturate; trout; trypsin; tryptophan; turn.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit turah "wounded, hurt;" Greek teirein "to rub, rub away;" Latin terere "to rub, thresh, grind, wear away," tornus "turning lathe;" Old Church Slavonic tiro "to rub;" Lithuanian trinu, trinti "to rub," Old Irish tarathar "borer," Welsh taraw "to strike."
Old English werian "to clothe, put on, cover up," from Proto-Germanic *wasīn- (source also of Old Norse verja, Old High German werian, Gothic gawasjan "to clothe"), from PIE *wos-eyo-, suffixed form of *wes- (2) "to clothe," extended form of root *eu- "to dress."
The Germanic forms "were homonyms of the vb. for 'prevent, ward off, protect' (Goth. warjan, O.E. werian, etc.), and this was prob. a factor in their early displacement in most of the Gmc. languages" [Buck]. It shifted from a weak verb (past tense and past participle wered) to a strong one (past tense wore, past participle worn) in 14c. on analogy of rhyming strong verbs such as bear and tear. Secondary sense of "use up, gradually damage" (late 13c.) is from effect of continued use on clothes. To wear down (transitive) "overcome by steady force" is from 1843. To wear off "diminish by attrition or use" is from 1690s.