Fed
early 20th century: abbreviation of federal. The abbreviation fed had previously been used in the late 18th century to denote a member of the Federalist Party, who advocated a union of American colonies after the War of Independence.
wiktionary
Clipping of federal.
Clipping of federation.
fed
etymonline
fed (adj.)
past-participle adjective from feed (v.). Fed up "surfeited, disgusted, bored," is British slang first recorded 1900 (some early uses connect it to the Boer War), extended to U.S. by World War I; probably from earlier phrases like fed up to the back teeth. Earlier it was used of livestock, "fatten up by feeding." The notion probably is the same one in to have had enough "to have had too much."
fed (n.)
1788, short for Federalist; as colloquial for "official of the federal government," from 1916; especially, since 1930s, of FBI agents.
