Definition of principle

• n. - Beginning; commencement.
• n. - A source, or origin; that from which anything proceeds; fundamental substance or energy; primordial substance; ultimate element, or cause.
• n. - An original faculty or endowment.
• n. - A fundamental truth; a comprehensive law or doctrine, from which others are derived, or on which others are founded; a general truth; an elementary proposition; a maxim; an axiom; a postulate.
• n. - A settled rule of action; a governing law of conduct; an opinion or belief which exercises a directing influence on the life and behavior; a rule (usually, a right rule) of conduct consistently directing one's actions; as, a person of no principle.
• n. - Any original inherent constituent which characterizes a substance, or gives it its essential properties, and which can usually be separated by analysis; -- applied especially to drugs, plant extracts, etc.
• v. t. - To equip with principles; to establish, or fix, in certain principles; to impress with any tenet, or rule of conduct, good or ill.