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.
principal: the head of a school, or the most important person/thing.
Tip: “principle” = rule; “principal” = person or main.
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 ‘principle’ and ‘principal’
| Word | Example Sentences |
|---|---|
| principle (noun) |
Always follow strong principle. The principle of supply and demand affects prices. “Treat others as you’d like to be treated” is a principle I adhere to. |
| principal (noun/adjective) |
The principal spoke at the assembly. The principal aim is clean energy. Chocolate is the principal ingredient here. |
Similar words
| Word | Synonyms |
|---|---|
| principle | truth, proposition, fundamental, essence, axiom, philosophy, ideology, theory, basis, postulate, tenet, concept |
| principal (adjective) | chief, primary, leading, foremost, predominant, dominant, (most) prominent, key, vital, crucial, first |
| principal (noun) | boss, chief, chairman/chairwoman, manager, director, president, head, CEO |
Origin of principle & principal
| Word Form | Examples |
|---|---|
| Other | 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 today’s use of the word, principal typically means the principal or head of a school.
More confusing words
Worksheet: Word choice
The school’s ______ greeted the students at the door.
Honesty is an important ______ to live by.
The ______ reason for the meeting is to discuss safety.
He refuses to lie on ______.
She paid both interest and ______ on her loan.
FAQs
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. "How to Use Principle or Principal? (Word Choice, Examples)." Grammarflex, Aug 24, 2025, https://grammarflex.com/principle-or-principal/.
