The fifth or last and highest essence or power in a natural body. See Ferment oils, under Ferment. (Obs.) Note: The ancient Greeks recognized four elements, fire, air, water, and earth. The Pythagoreans added a fifth and called it nether, the fifth essence, which they said flew upward at creation and out of it the stars were made. The alchemists sometimes considered alcohol, or the ferment oils, as the fifth essence.