principal
Americanadjective
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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.
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of, of the nature of, or constituting principal or capital.
Though our portfolio has seen losses, the principal investment remains untouched.
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Geometry. (of an axis of a conic) passing through the foci.
noun
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principals
plural
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a chief or head.
- Synonyms:
- leader
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the head or director of a school or, especially in England, a college.
- Synonyms:
- master, dean, headmaster
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a person who takes a leading part in any activity, as a play; chief actor or doer.
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the first player of a division of instruments in an orchestra (excepting the leader of the first violins).
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something of principal or chief importance.
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Law.
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a person who authorizes someone else, such as an agent, to represent them.
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a person directly responsible for a crime, either as an actual perpetrator or as an abettor present at its commission.
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a person primarily liable for an obligation, in contrast with an endorser, or the like.
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the main body of an estate, or the like, as distinguished from income.
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Finance. a capital sum, as distinguished from interest or profit.
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Music.
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an organ stop.
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the subject of a fugue.
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(in a framed structure) a member, as a truss, upon which adjacent or similar members depend for support or reinforcement.
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each of the combatants in a duel, as distinguished from the seconds.
adjective
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first in importance, rank, value, etc; chief
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denoting or relating to capital or property as opposed to interest, etc
noun
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a person who is first in importance or directs some event, action, organization, etc
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(in Britain) a civil servant of an executive grade who is in charge of a section
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law
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a person who engages another to act as his agent
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an active participant in a crime
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the person primarily liable to fulfil an obligation
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the head of a school or other educational institution
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(in Scottish schools) a head of department
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finance
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capital or property, as contrasted with the income derived from it
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the original amount of a debt on which interest is calculated
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a main roof truss or rafter
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music
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the chief instrumentalist in a section of the orchestra
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one of the singers in an opera company
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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
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the leading performer in a play
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
Inflected Forms
Nouns
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.
Vocabulary lists containing principal
Some Tricky Homonyms
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A Graduation Lexicon
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Brown v. Board of Education of Topeka (1954)
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Finally, Mercedes team principal Toto Wolff decided he was ready for the step up to Formula One ahead of last season and handed him the seat vacated by seven-time world champion Lewis Hamilton.
From The Wall Street Journal ● Nov. 2, 2026
UC San Diego helped establish the observatory, and Brian Keating, a Distinguished Professor of Physics at the university, serves as its principal investigator.
From Science Daily ● Nov. 2, 2026
Margaret confronts the principal and tells him that Carrie was rattled by the drill and that the whole exercise is traumatizing to students.
From Salon ● Oct. 30, 2026
Tracy Woo, a principal analyst at Forrester, said Alphabet's disappointing search business results "highlights the challenge of funding massive AI investments while maintaining the strength of established businesses."
From BBC ● Oct. 29, 2026
“So if I were the principal, and I needed to check on the well-being or current location of any of my students, I’d naturally need to log on to my computer,” Nurse Beverly said.
From "The School for Whatnots" by Margaret Peterson Haddix
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And the union representative for school principals, Nicolas Bonnet, told broadcaster franceinfo that "to get out of this crisis, we will need something more than simple consultation periods".
From Barron's ● Oct. 7, 2026
The principals settled on hosting Collins for a publicity event at Navatek’s Maine headquarters in August 2019, where she posed for pictures with Kao and a model of the company’s experimental boat.
From Salon ● Sep. 23, 2026
To scratch that fully voyeuristic itch, we often have to wait for merger and dealmaker principals to talk for themselves: the sit-down broadcast interviews; the expansive anecdotes from a panel stage.
From The Wall Street Journal ● Sep. 19, 2026
There have been some concerns this will place more pressure on school principals and teachers who are SEN coordinators in schools.
From BBC ● Sep. 6, 2026
She pulled herself straight and directed into his sleepy eyes the look she usually reserved for teachers and principals.
From "The Great Gilly Hopkins" by Katherine Paterson
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