A state of being mentally or emotionally disturbed; loss of composure or emotional control.
From de- + composure (calmness), ultimately from Latin componere (to put together). It's a deliberate reversal of 'composure,' meaning to undo one's calm state.
This word is relatively rare today, but it perfectly captures what happens when someone loses their cool—their emotions decompose into chaos, the opposite of being well-composed.
Complete word intelligence in one call. Free tier — 50 lookups/day.