Cupset refers to a situation in a sporting
competition (typically where a Cup is the top prize to be awarded) where a team from a lower league defeats a team from a higher league.
Severity ranges from "Minor Cupset" (i.e. a team beating another in the division above), "Major Cupset" (i.e. a team defeating another two or three divisions above them), to "Miraculous Cupset" (i.e. a team that isn't even a part of the 'official' league(s), defeats a team in the top divisions of the official league(s).)
"Cupset" is a contraction of the words "Cup Upset". It derives from the popular FA Cup
Competition run by the
Football Association for English football clubs, but can theoretically be used for any competition with similar league styles.
"Do you
remember when Southend United beat
Manchester United in the League Cup? What a cupset that was."
"As it stands, it's Liverpool nil, Stevenage one, and with only
five minutes to play, Liverpool are looking at a major cupset."