What is the meaning of Coolness?

Moderate chilliness.

Calmness, confidence, or level-headedness.

Conflict or hostility or an instance of such that stands in contrast to expected friendliness or interest.

Indifference or an instance of indifference; lack of friendliness or interest not necessarily rising to hostility.

Social advantage or enviability, typically due to traits like popularity, confidence, skill, or fashion.

Source: wiktionary.org