elementary

adjective

1. pertaining to or dealing with elements, rudiments, or first principles: an elementary grammar.
2. of or relating to an elementary school: elementary teachers.
3. of the nature of an ultimate constituent; simple or uncompounded.
4. pertaining to the four elements, earth, water, air, and fire, or to the great forces of nature; elemental.
5. Chemistry. of or noting one or more elements.

adjective

1. not difficult; simple; rudimentary
2. of or concerned with the first principles of a subject; introductory or fundamental
3. maths (of a function) having the form of an algebraic, exponential, trigonometric, or a logarithmic function, or any combination of these
4. chem another word for elemental (def. 5)