Principle

noun
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.
Chemistry. a constituent of a substance, especially one giving to it some distinctive quality or effect.
13.
Obsolete. beginning or commencement.
Idioms
14.
in principle, in essence or substance; fundamentally:
to accept a plan in principle.
15.
on principle,

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.
according to a fixed rule, method, or practice:
He drank hot milk every night on principle.

noun
1.
a standard or rule of personal conduct: a man of principle
2.
(often pl) a set of such moral rules: he’d stoop to anything, he has no principles
3.
adherence to such a moral code; morality: it’s not the money but the principle of the thing, torn between principle and expediency
4.
a fundamental or general truth or law: first principles
5.
the essence of something: the male principle
6.
a source or fundamental cause; origin: principle of life
7.
a rule or law concerning a natural phenomenon or the behaviour of a system: the principle of the conservation of mass
8.
an underlying or guiding theory or belief: the hereditary principle, socialist principles
9.
(chem) a constituent of a substance that gives the substance its characteristics and behaviour: bitter principle
10.
in principle, in theory or essence
11.
on principle, because of or in demonstration of a principle
noun
1.
(Christian Science) another word for God

principle prin·ci·ple (prĭn’sə-pəl)
n.

A basic truth, law, or assumption.

A rule or law concerning the functioning of natural phenomena or mechanical processes.

One of the elements composing a chemical compound, especially one that gives some special quality or effect.

The essential ingredient in a drug.