Definition from Wiktionary, the free dictionary
This entry suggests fed up comes from the verb feed, which is correct but does not help explain why fed-up has this particular meaning (an oddity of the English language)?
- It’s not an oddity of "fed up", it’s one of the common senses of up (as in used up, finished up, burned up, paid up, heated up, made up, drank up, and so on). If you "feed" (in the figurative sense) someone something until the point of saturation, he will be "fed up". Russian has almost an exact equivalent in надоедать (на-+до-+едать), to be fed up. —Stephen 12:32, 13 August 2007 (UTC)