Elementary

(a.) Having only one principle or constituent part; consisting of a single element; simple; uncompounded; as, an elementary substance.

Elementary - Other Definitions

(a.) Having only one principle or constituent part; consisting of a single element; simple; uncompounded; as, an elementary substance.
(a.) Pertaining to, or treating of, the elements, rudiments, or first principles of anything; initial; rudimental; introductory; as, an elementary treatise.
(a.) Pertaining to one of the four elements, air, water, earth, fire.