Principle (noun)

1. A fundamental truth or law that serves as the basis for a system of belief or behavior.
2. A fundamental quality or attribute that is inherent in something.
3. A moral rule or belief that governs a person's behavior.
4. A basic rule or law that applies in a particular field of study.

Origin:

The word 'principle' comes from the latin word 'principium' which means 'beginning, source, or foundation.'.

Examples:

1. The principle of equality is one of the core values of our democracy.
2. The principle of cause and effect is a fundamental concept in physics.
3. She lived her life by the principles of honesty and fairness.
4. The principle of conservation of energy states that energy cannot be created or destroyed.
5. The company operates on the principle of putting the customer first.