adjective Feeling unwell, nauseated, or ready to vomit.
His stomach was upset, so he didn't want to move.
noun Disturbance or disruption.
My late arrival caused the professor considerable upset.
noun An unexpected victory of a competitor or candidate that was not favored to win.
noun An overturn.
"collision and upset": impact with another object or an overturn for whatever reason.
noun An upset stomach.
noun 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.
noun 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.