essentialism

The idea, opposite to existentialism, that things have essences. For instance, in an essentialist view, there is an essense "horse" that exists seperately from any given individual horse; actual horses are just an instantiation of the essential concept "horse". In an essentialist view, it is the essences which are the true reality, and actual objects (or people) are just instantiations of those essences; "Essence precedes existence".

contrast with existentialism; the idea that any thing that is a thing has the (predetermined) essence of that thing. What? Say, a chair has chairness. Its essence not only determines what it is, but what it will be and do. (Raising the question: is a broken chair still a chair?) The essence of water is wetness- you can't have dry water (even if it would be more portable, and easy to prepare). The essence of a woman (as a woman) is feminity. The essence is related to the ideal, in Platonic terms.
Disclaimer: just because i'm noding it doesn't mean i agree with it!