The Collaborative International Dictionary of English v.0.48:

Detritus \De*tri"tus\, n. [F. d['e]tritus, fr. L. detritus, p.
   p. of deterere. See Detriment.]
   1. (Geol.) A mass of substances worn off from solid bodies by
      attrition, and reduced to small portions; as, diluvial
      detritus.
      [1913 Webster]

   Note: For large portions, the word d['e]bris is used.
         [1913 Webster]

   2. Hence: Any fragments separated from the body to which they
      belonged; any product of disintegration.
      [1913 Webster]

            The mass of detritus of which modern languages are
            composed.                             --Farrar.
      [1913 Webster]

WordNet (r) 3.0 (2006):

detritus
    n 1: the remains of something that has been destroyed or broken
         up [syn: debris, dust, junk, rubble, detritus]
    2: loose material (stone fragments and silt etc) that is worn
       away from rocks

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "detritus":
   afterglow, afterimage, alluvion, alluvium, balance, breccia, butt,
   butt end, candle ends, chaff, debris, deposit, diluvium, drift,
   end, fag end, filings, fossil, grain, granule, granulet, gravel,
   grit, holdover, husks, leavings, leftovers, loess, moraine,
   odds and ends, offscourings, orts, parings, rags, refuse, relics,
   remainder, remains, remnant, residue, residuum, rest, roach,
   rubbish, ruins, rump, sand, sawdust, scourings, scraps, scree,
   sediment, shadow, shavings, shingle, silt, sinter, straw, stubble,
   stump, survival, sweepings, trace, vestige, waste