attrition

(noun) erosion by friction. Synonyms: abrasion, corrasion, detrition.

(noun) the wearing down of rock particles by friction due to water or wind or ice. Synonyms: grinding, abrasion, detrition.

(noun) sorrow for sin arising from fear of damnation. Synonyms: contrition, contriteness.

(noun) a wearing down to weaken or destroy. Example: "A war of attrition."

(noun) the act of rubbing together; wearing something down by friction.