early 14c., "throw down or fall with force," perhaps from a Scandinavian source (cf. Danish dumpe, Norwegian dumpa "to fall suddenly"). The sense of "unload en masse" is first recorded in American English 1784. That of "discard, abandon" is from 1919. Related: Dumped; dumping. Dump truck is from 1930.
"place where refuse is dumped," 1865, originally of mining operations, from dump (v.). Meaning "any shabby place" is from 1899. Meaning "act of defecating" is from 1942.
To criticize harshly, often unfairly; complain and carp at; put down: If he does something right, I'm not going to dump on him/ Don't dump on the teachers we have/ an acknowledgement of the fact that he had dumped on us all year
[1940s+; perhaps fr dump, ''defecation'']
[origin uncertain; perhaps related to a Scandinavian term meaning ''to fall suddenly,'' the connection being the tipping out of a load from a cart]