Noah Webster's New International Dictionary of the English Language

1. (n.) A source, or origin; a fundamental truth, proposition or law.

2. (n.) Beginning; commencement.

3. (n.) An original faculty or endowment.

4. (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.

5. (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.

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.