(uncountable) Disturbance or disruption.

(countable, sports, politics) An unexpected victory of a competitor or candidate that was not favored to win.

(automobile insurance) An overturn.

An upset stomach.

(mathematics) An upper set; a subset (X,≤) of a partially ordered set with the property that, if x is in U and x≤y, then y is in U.

(aviation) The dangerous situation where the flight attitude or airspeed of an aircraft is outside the designed bounds of operation, possibly resulting in loss of control.

(transitive) To make (a person) angry, distressed, or unhappy.

(transitive) To disturb, disrupt or adversely alter (something).

(transitive) To tip or overturn (something).

(transitive) To defeat unexpectedly.

(intransitive) To be upset or knocked over.

To thicken and shorten, as a heated piece of iron, by hammering on the end.

To shorten (a tire) in the process of resetting, originally by cutting it and hammering on the ends.

(of a person) Angry, distressed, or unhappy.

(of a stomach or gastrointestinal tract, referred to as stomach) Feeling unwell, nauseated, or ready to vomit.