Definitions for upsetter
Random House Webster's College Dictionary
up•setʌpˈsɛt; ˈʌpˌsɛt(v., adj.; n.; v.; adj.)-set, -set•ting
to upset a glass of milk.
to disturb mentally or emotionally; distress:
The accident upset her.
to disturb completely; throw into disorder:
to upset a plan.
to disturb physically.
to defeat (an opponent that is favored), as in politics or sports.
(v.i.)to become upset or overturned.
(n.)an upsetting or instance of being upset; overturn; overthrow.
the unexpected defeat of an opponent that is favored.
a nervous, irritable state of mind.
a disturbance or disorder.
Origin of upset:
an unexpected winner; someone who defeats the favorite competitor
One who upsets (something); a disrupter.
A person or device that turns something upside down