That which is required for continued existence or function.
Blood that is needed for continued life; blood regarded as the seat of life.
A source, or origin; that from which anything proceeds; fundamental substance or energy; primordial substance; ultimate element, or cause.
A fundamental essence, particularly one producing a given quality.
A rule used to choose among solutions to a problem.
A rule or law of nature, or the basic idea on how the laws of nature are applied.
Bernoulli's Principle
An original faculty or endowment.
A fundamental assumption or guiding belief.
Moral rule or aspect.
To equip with principles; to establish, or fix, in certain principles; to impress with any tenet or rule of conduct.