essance - n.
1 the indispensable quality or element identifying a thing or determining its character; fundamental nature or inherent characteristics.
2 a an extract obtained by distillation etc., esp. a volatile oil. b a perfume or scent, esp. made from a plant or animal substance.
3 the constituent of a plant that determines its chemical properties.
4 an abstract entity; the reality underlying a phenomenon or all phenomena.

in essence fundamentally. of the essence indispensable, vital. [ME f. OF f. L essentia f. esse be]