What is the meaning of Quintessence?

A thing that is the most perfect example of its type; the most perfect embodiment of something; epitome, prototype.

A pure substance.

The essence of a thing in its purest and most concentrated form.

The fifth alchemical element, or essence, after earth, air, fire, and water that fills the universe beyond the terrestrial sphere.

A hypothetical form of dark energy postulated to explain observations of an accelerating universe.

To reduce to its purest and most concentrated essence.

quintessence (all senses)

Source: wiktionary.org