AXIOM and THEOREM

AXIOM      :       

A self evident of truth ; A widely accepted saying

"Everything that is living dies" is an popular axiom

Memory key

Axiom meaning we may not know but we know it ambiguous meaning so I just revised it.

Or remember it is an opposite to theorem. Usually we will be asked in school to prove theorems but not axioms.

Application

Axiom word in geometry says that is not need to be proved as it is self-evident, obvious 

And theorem means that it is not self evident and needs to be proved.