Note:  Do not rely on this information. It is very old.


Essence (Lat. essentia), the informing spirit of a thing; that which makes it what it is. In a metaphysical sense it is equivalent to the real nature of a class as expressed in the definition. In a physical sense it was said to be a quintessence or some fifth thing apart from but underlying the four elements. The word is used in chemistry generally to denote an alcoholic solution of the essential oil of a substance.