PRIN'CIPLE, n. [L. principium, beginning.]

1. In a general sense, the cause, source or origin of any thing; that from which a thing proceeds; as, the principle of motion; the principles of action. – Dryden.
2. Element; constituent part; primordial substance. Modern philosophers suppose matter to be one simple principle, or solid extension diversified by its various shapes. – Watts.
3. Being that produces any thing; operative cause. The soul of man is an active principle. – Tillotson.
4. In science, a truth admitted either without proof, or considered as having been before proved. In the former sense it is synonymous with axiom; in the latter, with the phrase, established principle.
5. Ground; foundation; that which supports an assertion, an action, or a series of actions or of reasoning. On what principle can this be affirmed or denied? He justifies his proceedings on the principle of expedience or necessity. He reasons on sound principles.
6. A general truth; a law comprehending many subordinate truths; as, the principles of morality, of law, of government, &c.
7. Tenet; that which is believed, whether truth or not, but which serves as a rule of action or the basis of a system, the principles of the Stoics, or of the Epicureans.
8. A principle of human nature, is a law of action in human beings; a constitutional propensity common to the human species. Thus it is a principle of human nature to resent injuries and repel insults.

1. To establish or fix in tenets; to impress with any tenet, good or ill; chiefly used in the participle. Men have been principled with an opinion, that they must not consult reason an things of religion. – Locke.
2. To establish firmly in the mind. – Locke.

1. Beginning; commencement.
   
   
   [Obs.]

   Doubting sad end of principle unsound. Spenser.

2. To equip with principles] to establish, or fix, in certain principles; to impress with any tenet, or rule of conduct, good or ill.
   
   

   Governors should be well principled. L'Estrange.

   Let an enthusiast be principled that he or his teacher is inspired. Locke.

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

   The soul of man is an active principle. Tillotson.

4. An original faculty or endowment.
   
   

   Nature in your principles hath set [benignity]. Chaucer.

   Those active principles whose direct and ultimate object is the communication either of enjoyment or suffering. Stewart.

5. 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.
   
   

   Therefore, leaving the principles of the doctrine of Christ, let us go on unto perfection. Heb. vi. 1.

   A good principle, not rightly understood, may prove as hurtful as a bad. Milton.

6. 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.
   
   

   All kinds of dishonesty destroy our pretenses to an honest principle of mind. Law.

7. 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.
   
   

   Cathartine is the bitter, purgative principle of senna. Gregory.

   Bitter principle, Principle of contradiction, etc. See under Bitter, Contradiction, etc.