In a calm, controlled, and composed manner; with emotional stability and grace under pressure.
From composed (past participle of compose, with the sense 'to put oneself together') plus -ly. The word evolved to describe outward calm, suggesting someone has literally 'composed' themselves.
The irony of 'composedly' is that it describes the opposite of what composers actually experience—Mozart and Beethoven were famously volatile, yet the word suggests serene control, not creative turbulence!
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