What does alluvion mean?
The definition of alluvion
Al*lu”vi*on, n.
Etym: [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.