Main Page | See live article | Alphabetical index In mathematics, a primitive notion is something that is not defined in terms of previously defined terms. That is, it is something that is taken to be true as an axiom rather than something that can be proved from a set of further axioms. For example in naive set theory, the notion of the existence of the empty set is primitive. For a more formal discussion of the foundations of mathematics see the axiomatic set theory article. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.