in principle, in essence or substance; fundamentally: to accept a plan in principle.
    on principle,
    1. 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.
    2. according to a fixed rule, method, or practice: He drank hot milk every night on principle.

Origin of principle

1350–1400; Middle English, alteration of Middle French principe or Latin prīncipium, on the analogy of manciple. See principium
Can be confusedprincipal principle (see usage note at principal) (see synonym study at the current entry)

Synonyms for principle

Synonym study

1–3. Principle, canon, rule imply something established as a standard or test, for measuring, regulating, or guiding conduct or practice. A principle is a general and fundamental truth that may be used in deciding conduct or choice: to adhere to principle. Canon, originally referring to an edict of the Church (a meaning that it still retains), is used of any principle, law, or critical standard that is officially approved, particularly in aesthetics and scholarship: canons of literary criticism. A rule, usually something adopted or enacted, is often the specific application of a principle: the golden rule.

Usage note Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for principles

Contemporary Examples of principles

Historical Examples of principles

British Dictionary definitions for principles



Christian Science another word for God



a standard or rule of personal conducta man of principle
(often plural) a set of such moral ruleshe'd stoop to anything; he has no principles
adherence to such a moral code; moralityit's not the money but the principle of the thing; torn between principle and expediency
a fundamental or general truth or lawfirst principles
the essence of somethingthe male principle
a source or fundamental cause; originprinciple of life
a rule or law concerning a natural phenomenon or the behaviour of a systemthe principle of the conservation of mass
an underlying or guiding theory or beliefthe hereditary principle; socialist principles
chem a constituent of a substance that gives the substance its characteristics and behaviourbitter principle
in principle in theory or essence
on principle because of or in demonstration of a principle

Word Origin for principle

C14: from Latin principium beginning, basic tenet


Principle and principal are often confused: the principal (not principle) reason for his departure; the plan was approved in principle (not in principal)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for principles



late 14c., "origin, source, beginning; rule of conduct; axiom, basic assumption; elemental aspect of a craft or discipline," from Anglo-French principle, Old French principe "origin, cause, principle," from Latin principium (plural principia) "a beginning, commencement, origin, first part," in plural "foundation, elements," from princeps (see prince). Used absolutely for (good or moral) principle from 1650s.

It is often easier to fight for principles than to live up to them. [Adlai Stevenson, speech, New York City, Aug. 27, 1952]

Scientific sense of "general law of nature" is recorded from 1802. The English -l- apparently is by analogy of participle, etc.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for principles




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.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Idioms and Phrases with principles


see in principle; on principle.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.