Elementary

Part of speech: adjective (a.)

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

2. Pertaining to, or treating of, the elements, rudiments, or first principles of anything; initial; rudimental; introductory; as, an elementary treatise.

3. Pertaining to one of the four elements, air, water, earth, fire. "Some luminous and fiery impressions in the elementary region." J. Spencer.