early 14c., "throw down or fall with force, drop (something or someone) suddenly," not found in Old English, perhaps from a Scandinavian source (compare Danish dumpe "fall hard," Norwegian dumpa "to fall suddenly," Old Norse dumpa "to beat").
The sense of "unload en masse, cause to fall out by tilting up a cart, etc." is recorded in American English by 1784. That of "discard, abandon" is from 1919. Economics sense of "export or throw on the market in large quantities at low prices" is by 1868. Related: Dumped; dumping. Dumping ground is by 1842.
"place where refuse is dumped, pile or heap of refuse matter," 1865, originally of mining operations, from dump (v.). In reference to sites for discarding domestic trash by 1872. Dumping-ground is by 1857. Meaning "any shabby place" is from 1899. Military sense of "collection of ammunition, equipment, etc. deposited in a convenient place for later use" is by 1915. Meaning "act of defecating" is from 1942. Dump-truck is from 1930.