It seems possible that an interesting thread might be developed concerning the origins, differences among cultures, and the various names for the concept "cool"
I think that it basically refers to control of emotions.
Control suggests a source of strength, lack of control, weakness.
Imagine two very primitive men meeting unexpectedly. If one is calm, and the other shows fear, the calm one has an advantage.
The Greeks allegedly had a word for everthing. What was their equivalent of "cool" ?
The Latin aequanimitas was a broad philosophical term.
So do any of you have ideas about how the concept of "cool" developed? And the shades of meaning in the various closely related words? And the differences in various cultures?