From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( 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.

(2): ( n.) Beginning; commencement.

(3): ( n.) A source, or origin; that from which anything proceeds; fundamental substance or energy; primordial substance; ultimate element, or cause.

(4): ( n.) An original faculty or endowment.

(5): ( 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.

(6): ( 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.

(7): ( 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.

Charles Buck Theological Dictionary [2]

An essential truth from which others are derived: the ground or motive of action.

See Disposition and DOCTRINE.