An antiessentialist is a person who opposes essentialism - the view that objects have properties that are essential to them, or the theory that human beings are good by nature and that evil is the product of society.
An antiessentialist is someone who rejects the idea that things have inherent or fixed qualities. They believe that characteristics and categories are socially constructed and context-dependent, rather than being universal or essential traits of individuals or groups. Antiessentialism is often associated with postmodernism and seeks to challenge traditional notions of identity and truth.