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.

---

noun

• principals
  plural

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

---

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.

---

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 ).

Synonym Usage

See capital ¹.

Other Word Forms

Derived Forms

• principalship
  noun
• underprincipal
  noun

Inflected Forms

Nouns

• principals
  plural

Etymology

Origin of principal

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

Explanation

For an adjective that points to the main or most important thing, your best choice is principal. Is your principal goal for the summer to have fun or to earn some extra money? The word, principal, comes from the Latin principalis "first in importance" and is related to the title of prince. You can see the relation when you think about its meanings — the head of a school, the starring actor in a film, and the client of an agent. Don't confuse principal with its homophone principle, a moral rule or law of nature. If you talk about a country's principal exports, you mean the main ones.

Example Sentences

See Examples For:

principal principals

They’d get less in fees, and you’d probably start to notice that you’re digging into your principal a little bit as you go along.

From MarketWatch ● Aug. 14, 2026

Notable performances include the world premieres of a work choreographed by ex-New York City Ballet principal Jock Soto and a piece by contemporary dancer and choreographer Sidra Bell.

From The Wall Street Journal ● Aug. 9, 2026

St James Group took up the role of "principal designer" in 2015, which meant it had a "duty to co-ordinate matters in relation to health and safety", the court heard.

From BBC ● Aug. 7, 2026

Rob Enderle, principal analyst at Oregon-based Enderle Group, said he expects more layoffs at other TikTok U.S. office locations due to the new ownership.

From Los Angeles Times ● Aug. 6, 2026

Mr. Charley Lyons was the school’s vice principal, a social studies teacher, and the basketball coach.

From "The Smartest Kid in the Universe" by Chris Grabenstein

Among the principals, everyone—El-Sayed, Stevens, Chuck Schumer, the Democratic Senatorial Campaign Committee—quickly got on the same team.

From Slate ● Aug. 8, 2026

His extensive reporting for “Checkmate,” including the cooperation of its principals, gives the book a page-turning intimacy.

From The Wall Street Journal ● Jun. 3, 2026

"Schools have a duty of care to their pupils, which includes ensuring reasonable access to toilet facilities. This forms part of the pastoral care responsibilities of boards of governors and principals."

From BBC ● May 16, 2026

Expert Wound Care and its principals could be immediately reached for comment on Tuesday.

From Los Angeles Times ● Apr. 28, 2026

A couple of generations of principals, school superintendents, and school boards have pretty much just left him alone.

From "Drama High" by Michael Sokolove

Related Words

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