Pronunciation: (prin'su-pul), [key]
1. an accepted or professed rule of action or conduct: a person of good moral principles.
2. a fundamental, primary, or general law or truth from which others are derived: the principles of modern physics.
3. a fundamental doctrine or tenet; a distinctive ruling opinion: the principles of the Stoics.
4. principles, a personal or specific basis of conduct or management: to adhere to one's principles; a kindergarten run on modern principles.
5. guiding sense of the requirements and obligations of right conduct: a person of principle.
6. an adopted rule or method for application in action: a working principle for general use.
7. a rule or law exemplified in natural phenomena, the construction or operation of a machine, the working of a system, or the like: the principle of capillary attraction.
8. the method of formation, operation, or procedure exhibited in a given case: a community organized on the patriarchal principle.
9. a determining characteristic of something; essential quality.
10. an originating or actuating agency or force: growth is the principle of life.
11. an actuating agency in the mind or character, as an instinct, faculty, or natural tendency: the principles of human behavior.
12. Chem.a constituent of a substance, esp. one giving to it some distinctive quality or effect.
13. Obs.beginning or commencement.
14. in principle, in essence or substance; fundamentally: to accept a plan in principle.
15. on principle,
a. according to personal rules for right conduct; as a matter of moral principle: He refused on principle to agree to the terms of the treaty.
b. according to a fixed rule, method, or practice: He drank hot milk every night on principle.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.