The doctrine that at least some objects have essences; that is, they have some of their properties essentially, not just because they are described in a certain way (a bishop is essentially in holy orders, yet could be defrocked without ceasing to be himself) but because they must have those properties to be themselves.
You might perhaps have been of the opposite sex, while still being yourself, but might you have been a horse?
C Kirwan, 'How Strong are the Objections to Essence?', Proceedings of the Aristotelian Society (1970-71)
Discipline: Political Science
A belief about human nature.
There are 'essential' features of human character which constitute the timeless and universal foundations of human nature.
Depending on the version of this theory, this essence may divide people into males and females, or leaders and led; or unite them as all equally aggressive, or self-seeking, or co-operative.
Maggie Humm, The Dictionary of Feminist Theory (London, 1989)