Merriam-Webster Collegiate Dictionary - essentialism

 noun  Date: 1927  1. an educational theory that ideas and skills basic to a culture should be taught to all alike by time-tested methods — compare progressivism  2. a philosophical theory ascribing ultimate reality to essence embodied in a thing perceptible to the senses — compare nominalism  3. the practice of regarding something (as a presumed human trait) as having innate existence or universal validity rather than as being a social, ideological, or intellectual construct  • essentialist adjective or noun