Principle vs. Principal: Meaning and Examples

Definitions of Principle vs. Principal

Did you have a high school principal or principle? There’s only one right answer. The primary definitions for these words are:

• principle (n.): a basic truth or a rule governing behavior
• principal (n.): someone or something of primary importance (e.g. a high school principal)
  

There is only one definition for principle. However, principal can also mean:

• principal (n.): a sum of money, either invested or lent
• principal (adj.): the first or highest in importance

Consider this sentence to see how many ways you can use principal:

The principal investigator spoke to the elementary school principal about the principal still owed on the school’s loans.

Notice that even though each word means something different, you would never use principle in these cases. Only use principle when discussing a core belief or guiding rule.

Principle Used in a Sentence

Even though principle only has one definition, there are lots of ways to use it creatively in a sentence! Check out these examples of principle when describing rules or basic truths.

• He was a man of principle and good to his word.
• All internal combustion engines work on the same principles.
• The ambassador refused on principle to agree to the terms of the accord.
• There exist certain fundamental principles of human rights.
• Two principles of happiness are being kind and smiling a lot.
• Isaac Newton published his three laws of motion in his Mathematical Principles of Natural Philosophy.
• I do not agree with the principles of that religion.
• She ate granola every morning on principle.
• One example of a business principle is putting the customer's interests first.

Used in a Quote

Principles are deeply important in human history. They guide the fundamentals of government, large organizations, lifestyle choices, and religious beliefs. Here are some famous quotes that involve principles:

• "A people that values its privileges above its principles soon loses both." - Dwight D. Eisenhower
• "Those are my principles, and if you don't like them... well, I have others." - Groucho Marx
• "Rules are not necessarily sacred, principles are." - Franklin D. Roosevelt
• "My guiding principles in life are to be honest, genuine, thoughtful and caring." - Prince William
• "We must adjust to changing times and still hold to unchanging principles." - Jimmy Carter

Principal Used in a Sentence

Your most familiar use of principal might be that bossy guy who brought you into his office as a kid. But there are lots of ways to use the word principal in a sentence! Check out these examples that use the word as both a noun and an adjective.

Used as a Noun

You can use principal in a number of ways. As a noun, it can mean the most prominent person or thing, and it can also mean the amount borrowed in a loan. Some example sentences include:

• The principal of the school is retiring this year.
• First chair of the violins is the principal.
• When you take out a loan, the amount of money you borrowed is called the principal.
• The principal of the firm just gave everyone a raise.
• Mary was the principal in the television series for 10 years.
• The theater troupe had a dinner to honor its principals.
• Every quarter we have to pay interest on the principal.
• The corporation's principal was based in New York.
• The principal of the ballet had a flawless performance.
• If you don’t pay the principal on time, you might get behind on your payments.

Used as an Adjective

Unlike principle, you can use principal as an adjective as well as a noun. It relates to the noun definition of “most important or primary.” You can use principal as an adjective in the following ways:

• The principal element in the Earth's crust is oxygen.
• This only applies to the principal cities in the state.
• The principal amount of your investment should be at least $10,000.
• Air pollution is a principal cause of respiratory ailments.
• The president highlighted her principal concerns in her speech.
• He is the principal cellist in the orchestra.
• Eggs are the principal ingredient in quiche.

Used in a Quote

Because it has multiple meanings, principal pops up in quotes in different ways. Some quotes that include principal from famous artists and politicians include:

• "All animals, except man, know that the principal business of life is to enjoy it." - Samuel Butler
• "The principal problem facing our economy today is jobs." - Jim Sensenbrenner
• "My father was also a principal of a school and mother was a curriculum advisor. Both were educators." - Edwin Moses
• "The dollar is currently the principal reserve currency in the world." - Robert C. Solomon
• "Here is how I work: when I think that a film needs to have a principal theme, I search for a melody." - Michel Legrand

Similar-Sounding Words

Now you have seen how both principal and principle are used in sentences, you can better understand the difference between these two words. But there are lots of other words that are easy to mix up! Read a helpful article on the difference between affect and effect, or see if you can distinguish between weather and whether.