Principal vs. Principle: Understanding the Key Differences

Last Updated on December 6, 2023

Understanding the distinction between principal vs. principle is a vital part of effective communication. The number of English words that have the same pronunciation but mean different things can sometimes be troublesome when it comes to writing something. “Principal” and “principle” are no exception.

At first glance, these two words may seem strikingly similar, but upon closer examination, their meanings and usage differ significantly. The following paragraphs aim to shed some light on this distinction and help readers understand when to use each word correctly.

Principal and Principle: Understanding the Basics 

Principal vs. PrinciplePin

Key Takeaways

Principal (noun/adjective)

  • As a noun, refers to a person with a leading role or authority, such as a school principal, or a primary actor in a situation.
  • As an adjective, describes something as the foremost or highest in importance, for example, the principal reason for an event.

Principle (noun)

  • Always a noun, a principle refers to a foundational belief, rule, or guideline that influences actions and decisions.

To avoid confusion, remember our handy mnemonic: the word “pal” in principal can remind us of a “person” or “primary” factor, while principle with an “le” at the end relates to “rules” or “laws” we uphold.

Definition and Usage

Principal, as an adjective, means “most important” or “first.” It comes from the Latin word “princeps,” which means chief, beginning, or origin. As a noun, it refers to someone in a leadership position, typically the chief or executive officer of an educational institution, such as a school principal. Additionally, the term “principal” can also refer to someone with controlling authority or a legal obligation in a specific transaction.

Principle, on the other hand, is solely a noun. It refers to a fundamental truth, a code, or a law, and is often used to signify a moral rule or guideline that governs one’s behavior, conduct, or actions. Principles can also describe a general scientific, legal, or theoretical rule that aids in understanding how something works or is organized.

Here are some ways to remember when to use principal and principle:

  • If referring to a leader or authority figure, such as the head of a school, you should use “principal.” A helpful mnemonic is to think of the principal as your “pal” in school.
  • Use “principle” when talking about a moral rule, guideline, or governing law, such as “following one’s principles” or “the principles of democracy.”

Here are a few examples of how these words are used in different contexts:

Principal (adjective):

  • The principal ingredient in this dish is tomatoes.
  • Primary education is the principal focus of this organization.

Principal (noun):

  • The school principal gave a speech during the high school graduation ceremony.
  • She was the principal investor in the new company.

Principle (noun):

  • Honesty is an essential principle for building trust in any relationship.
  • The laws of physics are based on fundamental principles that have been tested and proven over time.

Helpful Tips

When you are trying to distinguish between “principal” and “principle,” keep these helpful tips in mind:

  1. Context Matters: Pay close attention to the context in which the word is used in order to understand which one is appropriate. “Principal” is often associated with a position of authority, a key figure within an organization, or the main investment sum in finance. “Principle,” on the other hand, typically refers to a fundamental rule or guideline, whether it’s a moral, scientific, or legal standard.
  2. Grammar Rules: Remember that “principal” can function as both a noun and an adjective, while “principle” functions only as a noun. Keep an eye on the surrounding words and context to determine when “principal” is being used as an adjective (meaning “main” or “primary”).
  3. Mnemonic Device: To help you remember the correct word, associate the ending of “principle” with “rule” – both words end in “le.” As for “principal,” think of the word “adjective” – they both contain an “a” in their ending.

In short, to distinguish between “principal” and “principle,” keep these main differences in mind:

  • “Principal” (adjective): Most important or primary.
  • “Principal” (noun): A person in authority (e.g. school principal) or the main investment sum in finance.
  • “Principle” (noun): A fundamental rule, guideline, or standard used to make decisions or judgments.

Examples of Principal vs. Principle

Examples of “Principal” in Sentences

  1. The principal of the school gave a speech at the graduation ceremony.
  2. She paid off the principal on her loan, reducing the amount of interest she would owe.
  3. As the principal investor, he had the largest share in the company.
  4. The principal idea behind the experiment was to test the theory of relativity.
  5. The principal violinist led the orchestra with an impressive solo performance.

Examples of “Principle” in Sentences

  1. She stood by her principles, even when it was difficult.
  2. The principle of equality is fundamental to a democratic society.
  3. He explained the principles of physics to the class in a simple way.
  4. The organization operates on the principle that everyone deserves access to education.
  5. The design was based on the principle of form following function.

Examples of Sentences that Use Both “Principal” and “Principle”

  1. The school principal emphasized the principle of respect among students and teachers.
  2. As the principal speaker, she discussed the core principles that guided her career.
  3. The company’s principal goal is to operate on the principle of sustainability.
  4. The principal challenge facing the team was adhering to the principle of fair play.
  5. The principal architect explained that the building was designed with the principle of energy efficiency in mind.

Principal vs. Principle: Practice and Exercises

Fill in the blank 

  1. The __________ of the school addressed the students during the assembly.
  2. Honesty is an important __________ that she lives by.
  3. The __________ amount of the loan does not include the interest.
  4. The scientific __________ behind the experiment was sound.
  5. As the __________ actor, he had the most lines to memorize.
  6. The __________ of aerodynamics are crucial for aircraft design.
  7. She was awarded the __________ of the year for her outstanding leadership.
  8. The __________ reason for the company’s success is its customer service.
  9. He explained the basic __________ of the legal system to the jury.
  10. The __________ of the fund receives a higher percentage of the profits.

Answer with Explanation 

  1. Answer: principal
    • Explanation: “Principal” in this context refers to the head of a school.
  2. Answer: principle
    • Explanation: “Principle” refers to a fundamental truth or proposition that serves as the foundation for a system of belief or behavior.
  3. Answer: principal
    • Explanation: “Principal” here means the original sum of money lent or invested, excluding any interest or profit.
  4. Answer: principle
    • Explanation: “Principle” is used to describe a fundamental truth that serves as the base for a system of belief, in this case, scientific reasoning.
  5. Answer: principal
    • Explanation: “Principal” as an adjective means first in order of importance; the main actor.
  6. Answer: principles
    • Explanation: “Principles” are fundamental truths or propositions that serve as the foundation for a system, in this case, the science of aerodynamics.
  7. Answer: principal
    • Explanation: “Principal” in this context is used as a noun to describe the head of a school or organization.
  8. Answer: principal
    • Explanation: “Principal” as an adjective means the most important; the main reason.
  9. Answer: principles
    • Explanation: “Principles” refer to the fundamental truths or propositions that serve as the foundation for a system, in this case, the legal system.
  10. Answer: principal
    • Explanation: “Principal” here is used in a financial context to mean the person who has a primary position in a transaction, receiving a higher profit share.

FAQs on Principal or Principle

Q: What is the difference between principal and principle?

A: “Principal” has two meanings: as an adjective, it refers to something that is most important or influential, and as a noun, it refers to a controlling authority, such as a school headmaster or a person in charge of certain things in a company. “Principle” is a rule, law, guideline, or fact.

Q: When should I use principal in a sentence?

A: Use “principal” when describing the highest level of importance, as in “The principal reason for our success is teamwork.” Or, use it as a noun to refer to a person in a leadership position, such as “The school principal addressed the issue promptly.”

Q: When should I use principle in a sentence?

A: Use “principle” when referring to a fundamental truth, rule, or belief that governs behavior or actions, such as “She followed the principle of honesty in all her dealings.”

Q: How can I remember the difference between principal and principle?

A: One helpful mnemonic device is to isolate “pal” from “principal” and recall that the “principal” is your “pal.” Additionally, remember that “principle” shares an “le” ending with the word “rule.”

Word Part of Speech Meaning
Principal Adjective / Noun Most important (A), authority or leader (N)
Principle Noun Rule, law, guideline, or fundamental truth that governs behavior

By understanding the grammatical differences between “principal” and “principle,” you can confidently use both in your writing and speech, ensuring accurate diction and clear communication.


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