principal

PRIN-si-puhl/ˈpɹɪnsɪpəl/

Noun pluralprincipals

Often confused with principle

16 meanings of principal

Practice

1
chiefadjective
Most important or main; ranking first among a group of things.
The principal cause of the delay was bad weather over the mountains.
Education was the principal aim of the new government policy.
UsageDon't confuse principal (main, chief) with principle (a rule or belief). Usually before the noun: the principal reason.
Similarmain, chief, primary
Oppositesecondary, minor, subsidiary
2
school headnouncountable or uncountable
The person who heads and manages a school, college, or university.
The principal suspended two students after the fight in the cafeteria.
Parents met with the principal to discuss the new bell schedule.
UsageSpelled principal (not ~~incorrect: principle~~), often in school principal.
Similarheadteacher, head, headmaster, headmistress
Note
Which institution a principal heads depends on the country. In the US, Canada, Ireland, Australia, New Zealand and the Philippines the word names the person running a school, often as school principal. Where it is not used this way, headteacher, headmaster or headmistress fill the role. In the UK and Canada the title also goes to the head of some colleges and universities, so a principal may lead either kind of institution.
3
original sumnoununcountable
The original sum of money invested or loaned, used as the base for calculating interest and returns.
The loan's principal was fifty thousand dollars, with interest added each month.
By overpaying every month, they reduced the principal far faster than scheduled.
UsageUsually the principal, set against interest: pay down the principal.
Similarcapital
Note
Lenders and borrowers set the principal against interest. Part of a typical mortgage payment reduces the principal and another part covers interest.
4
business ownernounCanadaUScountable or uncountable
A person who owns or is a partner in a business.
As a principal of the firm, she signed the contract herself.
Both principals agreed to reinvest the year's earnings into new equipment.
Similarproprietor, owner
Note
In the US and Canada a firm's principals are its owners or partners, the people the word proprietor would also fit. The usage sits close to the legal party behind an agent, since an owner is the one others act for. Here, though, the word names a stake in the business rather than a legal relationship.
Checked 1 Nov 2026 · 1 fact
Business owners may have others act on their behalf. en.wikipedia.org
5
person representednouncountable or uncountable
A person who authorizes another, the agent, to act on their behalf.
The principal instructed the agent to accept no offer below market value.
An agent must always act in the principal's best interest.
Similarclient
Oppositeagent
Note
The law of agency is built on a pair: the principal gives authority and the agent uses it. A client stands as principal to the attorney, and a seller stands as principal to the broker who negotiates for it. Lawyers also speak of a disclosed principal, meaning one whose identity is known to the other side. The term reaches as well to the person a gestor acts for in negotiorum gestio.
Checked 1 Nov 2026 · 5 facts
Agency involves a principal granting authority to an agent to act. en.wikipedia.org
A client is the principal in the attorney-client agency relationship. ctb.uscourts.gov
A seller is principal to the broker acting for that seller. en.wikipedia.org
A disclosed principal's identity is known to the other party. law.justia.com
The person for whom a gestor acts in negotiorum gestio is called the principal. en.wikipedia.org
6
main actornouncountable or uncountable
A leading performer, such as an actor in a main role, a dancer of the highest rank in a ballet company, or the leading player of an orchestra section.
The director cast a newcomer as a principal, with seasoned actors filling the smaller roles.
Both principals received a standing ovation after the finale.
Similarlead, star

Less common meanings

7
basic rulenounobsoletecountable or uncountable
An essential point or basic rule; a fundamental principle.
Set two classes of monitors to question each other; so that one may try to outquestion the other. Explain to them the principal of every subject they have to teach.
1847, Great Britain. Committee on Education, Minutes of the Committee of Council on Education
Note
To a modern reader this spelling looks like a mistake, and in this meaning it is obsolete. It survived long enough for the Committee of Council on Education's Minutes of 1847 to advise teachers to "explain to them the principal of every subject." Today the word principle carries this meaning, and principal used this way will look like a slip.
8
main criminalnouncountable or uncountable
The main participant who actually carries out a crime.
The jury found her guilty as the principal in the assault.
Two principals planned and executed the heist together.
Similarringleader
Oppositeaccessory
Note
Criminal law traditionally distinguishes the principal, who commits the offense or aids at the scene, from the accessory, who helps before or after it. Modern statutes can merge these categories. Gilmore and Wermuth's Modern American Law notes that accessories may be tried and punished even when the principal has never been prosecuted or has been acquitted. Ringleader is a looser, everyday neighbor of the term.
9
duel fighternouncountable or uncountable
Either of the two people who actually fight in a duel, as distinct from their seconds or attendants.
The two principals took their positions twelve paces apart.
As the challenged party, the principal had the right to choose weapons.
Similarduelist, combatant
Oppositesecond
10
adjectiveobsolete
Relating to a prince, or characteristic of one; princely.
But walkt at will, and wandred to and fro, / In the pride of his freedome principall.
1590, Edmund Spenser, The Faerie Queene
Note
English has lost this meaning, which tied the word directly to the prince. Edmund Spenser's Muiopotmos, printed in his Complaints (1591), has the butterfly Clarion, who "wandred too and fro, / In the pride of his freedome principall," where the word means princely and follows its noun in the Latinate way. Expect it only in older poetry; to say the same thing today, use princely.
Checked 1 Nov 2026 · 7 facts
Principal historically meant relating to a prince or princely. en.wiktionary.org
Edmund Spenser wrote Muiopotmos. talus.artsci.wustl.edu
Muiopotmos appeared in Complaints, first published in 1591. celm.folger.edu
The poem's butterfly is named Clarion. en.wikipedia.org
The text reads “wandred too and fro,” and the line ending “principall” ends with a colon. talus.artsci.wustl.edu
Principall means princely in this passage. gutenberg.org
Principall follows its noun, matching a possible Latin adjective position. en.wikipedia.org
11
noun
In computer security, an entity such as a user, device, or program that can be identified, verified, and granted specific access rights.
12
adjective
Selected from among the several values of a multi-valued function so that the function returns a single, definite value.
13
noun
A type of organ stop made up of flue pipes with a bright tone, also known as a diapason.
14
noun
The framework, usually a truss of timber or iron, that gives a roof its shape and strength; more loosely, the most important member of a piece of framing.
15
nounrare
In falconry, either of the first two long flight feathers at the tip of a hawk's wing.
The first two feathers - Principals
1856, John Henry Walsh, Manual of British Rural Sports
16
nounobsolete
One of the turrets or pinnacles of wax and lit tapers that formerly crowned the posts and center of a funeral hearse.

Practice

Can you tell the meanings of principal apart? Answer 3 quick questions from this page, or write your own sentence and AI will check it.

Origin

Latin prīncipālis passed into Old French as principal and from there into Middle English with the same spelling.