Meaning of “upset” - Learner’s Dictionary

upset

adjective uk us /ʌpˈset/

A2 unhappy or worried because something unpleasant has happened:

They'd had an argument and she was still upset about it.
Mike got very upset when I told him the news.
upset stomach/tummy

an illness in the stomach

(Definition of “upset adjective” from the Cambridge Learner’s Dictionary © Cambridge University Press)