A broad and basic rule or truth
Moral or ethical strength
A fundamental law
A belief or set of beliefs; often plural
Why couldn't Katie understand that there was a principle involved?
The basic principle was that those who worked hard would be rewarded.
The principle of energy makes it clear that the light emitted laterally is not a new creation, but only diverted from the main stream.
The principle of equality of nations that inhabit our country is strictly adhered by.
By one count, rice is the principle source of calories for about half the planet.