The Collaborative International Dictionary of English v.0.48:

Diluvium \Di*lu"vi*um\, n.; pl. E. Diluviums, L. Diluvia.
   [L. diluvium. See Dilute, Deluge.] (Geol.)
   A deposit of superficial loam, sand, gravel, stones, etc.,
   caused by former action of flowing waters, or the melting of
   glacial ice.
   [1913 Webster]

   Note: The accumulation of matter by the ordinary operation of
         water is termed alluvium.
         [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "diluvium":
   alluvion, alluvium, ash, cinder, clinker, debris, deposit,
   deposition, deposits, detritus, draff, dregs, drift, dross, ember,
   feces, froth, grounds, lees, loess, moraine, offscum, precipitate,
   precipitation, scoria, scree, scum, sediment, settlings, silt,
   sinter, slag, smut, soot, sublimate