Axiom  -  A statement about real numbers that is accepted as true without proof.

Deductive Reasoning  -  A form of reasoning by which each conclusion follows from the previous one; an argument is built by conclusions that progress towards a final statement.

Inductive Reasoning  -  A form of reasoning in which a conclusion is reached based on a pattern present in numerous observations.

Postulate  -  A statement about geometry that is accepted as true without proof.

Theorem  -  A statement in geometry that has been proved.

Undefined Terms  -  Terms that aren't defined, but instead explained; they form the foundation for all definitions in geometry.