Source : Webster's Revised Unabridged Dictionary (1913)

Alluvion \Al*lu"vi*on\, n. [F. alluvion, L. alluvio, fr. alluere
   to wash against; ad + luere, equiv. to lavare, to wash. See
   {Lave}.]
   1. Wash or flow of water against the shore or bank.

   2. An overflowing; an inundation; a flood. --Lyell.

   3. Matter deposited by an inundation or the action of flowing
      water; alluvium.

            The golden alluvions are there [in California and
            Australia] spread over a far wider space: they are
            found not only on the banks of rivers, and in their
            beds, but are scattered over the surface of vast
            plains.                               --R. Cobden.

   4. (Law) An accession of land gradually washed to the shore
      or bank by the flowing of water. See {Accretion}.

Source : WordNet®

alluvion
     n 1: gradual formation of new land, by recession of the sea or
          deposit of sediment
     2: the rising of a body of water and its overflowing onto
        normally dry land; "plains fertilized by annual
        inundations" [syn: {flood}, {inundation}, {deluge}]
     3: clay or silt or gravel carried by rushing streams and
        deposited where the stream slows down [syn: {alluvial
        sediment}, {alluvial deposit}, {alluvium}]