When to use “principle” and “principal”
Are you looking to describe a school headmaster, or a fundamental rule or tenet? If it’s the latter, then the word you’re probably looking for is principle. The former (a school headmaster) is principal.
The school’s principal announced the new rules for the year.
It is important to always act according to your ethical principles.
The principle investigator led the research team. instead of “principal” (main or most important) to describe an investigator)
The students were excited to meet the new principles of the school. instead of “principal” (school head) to refer to a person)
Principle vs. principal
While both principle and principal are pronounced the same, they are distinct in their meaning and the correct contexts in which they should be used.
| Examples with “principal” (adjective) | Examples with “principle” (noun) |
|---|---|
| Tourist revenue is now our principal source of wealth. | Stick to your principles and tell him you won’t do it. |
Principle is a noun that refers to, “a moral rule or a strong belief that influences your actions”; as in, “an important moral principle“.
Principal, on the other hand, is mostly used as an adjective to describe something or someone as the main or most important thing of a certain kind. We also use it as a noun to refer to someone in charge of a school.
The term principal is also used frequently in finance to refer to a sum of money that’s borrowed or lent, and which interest is paid towards: The winners are paid from the interest without even touching the principal.
Did you know? Principle vs. principal
Both principle and principal evolved from French, but are originally Latin. The adjective principal comes from the Latin principalis, meaning “first in importance; original, primitive”. The noun principle comes from the Latin word, principium, “a beginning, commencement, origin, first part,” in plural “foundation, elements”. Both share roots with other words in English like prime from primus meaning “first”.
Sentences with the noun ‘principle’
Upholding ethical principles is essential for maintaining trust in any organization.
The principle of supply and demand influences the pricing of goods and services.
She follows the principle of “work hard, play hard,” ensuring a balance between her professional and personal life.
The company’s success can be attributed to its adherence to customer-centric principles.
The golden rule, “treat others as you would like to be treated,” is a universal moral principle.
Sentences with principal
The principal of the school addressed the students during the morning assembly.
The principal aim of the project is to develop a sustainable source of clean energy.
The principal reason for the delay in the construction was the shortage of building materials.
The principal dancer captivated the audience with her graceful performance.
The principal ingredient in this recipe is chocolate, giving it a rich flavor.
To recall which is the person, remember the school **principal** is your **pal**, ending in “-pal.”.
Synonyms of principle
- truth
- proposition
- fundamental
- essence
- axiom
- philosophy
- ideology
- theory
- basis
- postulate
- tenet
- concept
Synonyms of principal
Synonyms with “principal” as an adjective:
- chief
- primary
- leading
- foremost
- predominant
- dominant
- (most) prominent
- key
- vital
- crucial
- first
Synonyms for principal as a noun:
- boss
- chief
- chairman/chairwoman
- manager
- director
- president
- head
- CEO
Origin of principle & principal
Late 14c., “origin, source, beginning” (a sense now obsolete), also “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”.
c. 1300, “main, principal, chief, dominant, largest, greatest, most important;” also “great, large,” from Old French principal “main, most important,” of persons, “princely, high-ranking” (11c.) and directly from Latin principalis “first in importance; original, primitive”.
c. 1300, “chief man, leading representative,” also “the most part, the main part;” also, in law, “one who takes a leading part or is primarily concerned in an action or proceeding;” from principal (adj.) or from or influenced by noun uses in Old French and Latin.
In review: principal and principle
Principal is both an adjective and a noun:
- As an adjective, principal describes something or someone as “most important, consequential, or influential: the region’s principal city“.
- As a noun, a principal refers to “a person of the highest authority or most important position in an organization, institution, or group.” In todayz’s use of the word, principal typically means the principal or head of a school.
Check out other commonly confused words
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- Insure, Ensure or Assure?
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Sources
- “Principal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/principal. Accessed 17 Aug. 2023.
- Harper, Douglas. “Etymology of principal.” Online Etymology Dictionary, https://www.etymonline.com/word/principal. Accessed 17 August, 2023.
- Harper, Douglas. “Etymology of principle.” Online Etymology Dictionary, https://www.etymonline.com/word/principle. Accessed 17 August, 2023.
Work Sheet
According to the post, what does the word “principle” most commonly refer to?
When “principal” is used as an adjective, what does it mean?
The post mentions a common incorrect usage: “The principle investigator led the research team.” Why is “principle” incorrect here?
According to the post, who is the “principal” at a school?
In the context of finance, what does “principal” refer to?
The school’s __________ announced the new dress code.
It is important to always act according to your ethical _________.
Tourist revenue is now our __________ source of wealth.
Upholding ethical __________ is essential for maintaining trust in any organization.
The winners are paid from the interest without even touching the __________.
Frequently Asked Questions
How do you refer to a school head?
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What does the noun “principle” mean?
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What is “principal” as an adjective?
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Is “principal” ever used for money?
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Can you use “principle” for a person?
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Yash, D. "The Difference Between Principle and Principal." Grammarflex, Jun 15, 2025, https://www.grammarflex.com/the-difference-between-principle-and-principal-explained-examples/.
