Quintessential (adjective)

1. Being the most perfect or typical example of a quality or class.
2. Being the essence or most essential element of something.

Origin:

From the latin quinta essentia, literally meaning "fifth essence", from the aristotelian notion of the five elements (earth, air, fire, water, and ether) that make up all things.

Examples:

1. He is the quintessential gentleman.
2. The little black dress is the quintessential item in a woman's wardrobe.
3. The Mona Lisa is the quintessential painting of the Renaissance.
4. The book is the quintessential guide to the subject.
5. The movie is the quintessential example of the genre.