axiom

IPA: ˈæksiʌm

(philosophy) A seemingly self-evident or necessary truth which is based on assumption; a principle or proposition which cannot actually be proved or disproved.
(logic, mathematics, proof theory) A fundamental assumption that serves as a basis for deduction of theorems; a postulate (sometimes distinguished from postulates as being universally applicable, whereas postulates are particular to a certain science or context).
An established principle in some artistic practice or science that is universally received.

Examples of "axiom" in Sentences

The belief that "actions speak louder than words" is a common axiom in the business world
In mathematics, the commutative property is considered an axiom because it is accepted without proof
One of the fundamental axioms of biology is that all living things are made up of cells
The Golden Rule, "treat others as you would like to be treated," is a moral axiom found in many cultures
The principle of supply and demand is a well-known economic axiom that explains market behavior