adjective
(of a person, predicative only) Angry, distressed, or unhappy
(of a stomach or gastrointestinal tract) Feeling unwell, nauseated, or ready to vomit.
noun
(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.
(basketry) A woven row supporting the foundation rods for the uprights of a basket.
verb
(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.
(obsolete) To set up; to put upright.
(metalworking) To thicken and shorten a soft or heated piece of metal, by forging or hammering on the end, to shape, for example, rivets or internal combustion engine valves.
To shorten (a tire) in the process of resetting, originally by cutting it and hammering on the ends.
(transitive, basketry) To support with an upset (type of woven row).