essence

Concise Oxford English Dictionary © 2008 Oxford University Press:
essence/ˈesns/

▶noun

• 1 the intrinsic nature or indispensable quality of something, which determines its character: conflict is the essence of drama.

  ■ Philosophy a property or group of properties of something without which it would not exist or be what it is.

• 2 an extract or concentrate obtained from a plant or other substance and used for flavouring or scent.

– phrases
in essence basically; fundamentally.
of the essence critically important.

– origin ME: via OFr. from L. essentia, from esse ‘be’.