The Collaborative International Dictionary of English v.0.48:

Attrition \At*tri"tion\, n. [L. attritio: cf. F. attrition.]
   1. The act of rubbing together; friction; the act of wearing
      by friction, or by rubbing substances together; abrasion.
      [1913 Webster]

            Effected by attrition of the inward stomach.
                                                  --Arbuthnot.
      [1913 Webster]

   2. The state of being worn. --Johnson.
      [1913 Webster]

   3. (Theol.) Grief for sin arising only from fear of
      punishment or feelings of shame. See Contrition.
      --Wallis.
      [1913 Webster]

WordNet (r) 3.0 (2006):

attrition
    n 1: erosion by friction [syn: abrasion, attrition,
         corrasion, detrition]
    2: the wearing down of rock particles by friction due to water
       or wind or ice [syn: grinding, abrasion, attrition,
       detrition]
    3: sorrow for sin arising from fear of damnation [syn:
       attrition, contrition, contriteness]
    4: a wearing down to weaken or destroy; "a war of attrition"
    5: the act of rubbing together; wearing something down by
       friction