principal

American  

[prin-suh-puhl] / ˈprɪn sə pəl /

adjective

1. first or highest in rank, importance, value, etc.; chief; foremost.

   The principal problem is a lack of money.

   She's the principal advisor on the council.

   Synonyms:

   preeminent, cardinal, main, leading, paramount, prime

   Antonyms:

   ancillary, secondary

2. of, of the nature of, or constituting principal or capital.

   Though our portfolio has seen losses, the principal investment remains untouched.

3. Geometry. (of an axis of a conic) passing through the foci.

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noun

1. a chief or head.

   Synonyms:

   leader

2. the head or director of a school or, especially in England, a college.

   Synonyms:

   master, dean, headmaster

3. a person who takes a leading part in any activity, as a play; chief actor or doer.

4. the first player of a division of instruments in an orchestra (excepting the leader of the first violins).

5. something of principal or chief importance.

6. Law.

   1. a person who authorizes someone else, such as an agent, to represent them.

   2. a person directly responsible for a crime, either as an actual perpetrator or as an abettor present at its commission.

7. a person primarily liable for an obligation, in contrast with an endorser, or the like.

8. the main body of an estate, or the like, as distinguished from income.

9. Finance. a capital sum, as distinguished from interest or profit.

10. Music.

    1. an organ stop.

    2. the subject of a fugue.

11. (in a framed structure) a member, as a truss, upon which adjacent or similar members depend for support or reinforcement.

12. each of the combatants in a duel, as distinguished from the seconds.

principal British  

/ ˈprɪnsɪpəl /

adjective

1. first in importance, rank, value, etc; chief

2. denoting or relating to capital or property as opposed to interest, etc

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noun

1. a person who is first in importance or directs some event, action, organization, etc

2. (in Britain) a civil servant of an executive grade who is in charge of a section

3. law

   1. a person who engages another to act as his agent

   2. an active participant in a crime

   3. the person primarily liable to fulfil an obligation

4. the head of a school or other educational institution

5. (in Scottish schools) a head of department

6. finance

   1. capital or property, as contrasted with the income derived from it

   2. the original amount of a debt on which interest is calculated

7. a main roof truss or rafter

8. music

   1. the chief instrumentalist in a section of the orchestra

   2. one of the singers in an opera company

   3. either of two types of open diapason organ stops, one of four-foot length and pitch and the other of eight-foot length and pitch

9. the leading performer in a play

principal Cultural  

1. The original amount of money lent, not including profits and interest.

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Commonly Confused

The noun principle and the noun and adjective principal are often confused. Although pronounced alike, the words are not interchangeable in writing. A principle is broadly “a rule of action or conduct” ( His overriding principle is greed ) or “a fundamental doctrine or tenet” ( Their principles do not permit the use of alcoholic beverages ). The adjective principal has the general sense “chief, first, foremost”: My principal objection is the cost of the project. The noun principal has among other meanings “the head or director of a school” ( The faculty supported the principal in her negotiations with the board ) and “a capital sum, as distinguished from interest or profit” ( The monthly payments go mostly for interest, leaving the principal practically untouched ).

Related Words

See capital ¹.

Other Word Forms

• principalship noun
• underprincipal noun

Etymology

Origin of principal

First recorded in 1250–1300; Middle English, from Latin prīncipālis “first, chief,” equivalent to prīncip- ( prince ) + -ālis -al ¹

Example Sentences

It was acting principal Fergal Friel who described their use by children as school's most serous issue in years.

From BBC • Apr. 3, 2026

Easter, the principal holiday of the Christian church, celebrates the resurrection of Jesus.

From Barron's • Apr. 2, 2026

The two picks were named co-CEOs while Overdeck and Siegel remained Two Sigma’s principal owners and co-chairmen, maintaining indirect control over the firm.

From The Wall Street Journal • Apr. 1, 2026

“The kids are so excited to have high school students here to run the ceremony,” Maple principal Meghann O’Weger said.

From Los Angeles Times • Mar. 31, 2026

It’s probably a good thing that I spilled the beans beforehand, because we’re pretty quiet and respectful when the principal makes the announcement.

From "Linked" by Gordon Korman

Related Words

• dominant
• key
• leading
• main
• major
• outstanding
• paramount
• predominant
• preeminent
• primary
• prime
• prominent