El`e*men"ta*ry (?), a. [L. elementarius: cf. F. élémentaire.] 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.

• Relating to the basic, essential or fundamental part of something.
  
• Relating to an elementary school.
  
• (physics) Relating to a subatomic particle.