1. A basic truth, law, or assumption: the principles of democracy.
a. A rule or standard, especially of good behavior: a man of principle.
b. The collectivity of moral or ethical standards or judgments: a decision based on principle rather than expediency.
3. A fixed or predetermined policy or mode of action.
4. A basic or essential quality or element determining intrinsic nature or characteristic behavior: the principle of self-preservation.
5. A rule or law concerning the functioning of natural phenomena or mechanical processes: the principle of jet propulsion.
6. Chemistry One of the elements that compose a substance, especially one that gives some special quality or effect.
7. A basic source. See Usage Note at principal.
With regard to the basics: an idea that is acceptable in principle.
According to or because of principle.
[Middle English, alteration of Old French principe, from Latin prīncipium, from prīnceps, prīncip-, leader, emperor; see per1 in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.