Definition of "upset" in English

adjective

1. (of a person, predicative only) Angry, distressed, or unhappy

   • He was upset when she refused his friendship.
   • My children often get upset with their classmates.

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

   • His stomach was upset, so he didn't want to move.
   • Bryan came home from school with an upset tummy.

noun

1. (uncountable) Disturbance or disruption.

   • My late arrival caused the professor considerable upset.

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

3. (automobile insurance) An overturn.

   • "collision and upset": impact with another object or an overturn for whatever reason.

4. An upset stomach.

5. (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.

6. (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.

7. (basketry) A woven row supporting the foundation rods for the uprights of a basket.

verb

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

   • I’m sure the bad news will upset him, but he needs to know.

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

   • Introducing a foreign species can upset the ecological balance.
   • The fatty meat upset his stomach.

3. (transitive) To tip or overturn (something).

   • 1924, W. D. Ross translator, Aristitle, Metaphysics, Book 1, Part 9, The Classical Library, Nashotah, Wisconsin, 2001. But this argument, which first Anaxagoras and later Eudoxus and certain others used, is very easily upset; for it is not difficult to collect many insuperable objections to such a view.

4. (transitive) To defeat unexpectedly.

   • Truman upset Dewey in the 1948 US presidential election.

5. (intransitive) To be upset or knocked over.

   • The carriage upset when the horse bolted.

6. (obsolete) To set up; to put upright.

   • R. of Brunne with sail on mast upset

7. (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.