Yes, upset is a Scrabble word!

Verb

1. Disturb the balance or stability of

2. Cause to lose one's composure

3. Move deeply

4. Cause to overturn from an upright or normal position

5. Form metals with a swage

6. Defeat suddenly and unexpectedly

Adjective

1. Afflicted with or marked by anxious uneasiness or trouble or grief

2. Thrown into a state of disarray or confusion

3. Used of an unexpected defeat of a team favored to win

4. Mildly physically distressed

5. Having been turned so that the bottom is no longer the bottom

Noun

1. An unhappy and worried mental state

2. The act of disturbing the mind or body

3. A physical condition in which there is a disturbance of normal functioning

4. A tool used to thicken or spread metal (the end of a bar or a rivet etc.) by forging or hammering or swaging

5. The act of upsetting something

6. An improbable and unexpected victory