principal

1 of 2

adjective

prin·​ci·​pal ˈprin(t)-s(ə-)pəl 

-sə-bəl

1

: most important, consequential, or influential : chief

the principal ingredient

the region's principal city

2

: of, relating to, or constituting principal or a principal (see principal entry 2)

principally

ˈprin(t)-sə-p(ə-)lē 

-sə-bə-lē

-splē

adverb

Principle vs. Principal: Usage Guide

Evidence of confusion between principle and principal can be found even in publications overseen by professional editors. To keep these words straight, remember that principle functions only as a noun, and in its most common uses refers to a basic rule or law, as in

a guiding principle

or

a matter of principle.

If you are looking for an adjective form of this word, you must use principled, as in

taking a principled stand.

Principal functions as both a noun and an adjective. The noun has various meanings referring to someone with controlling authority

the school principal

or in a leading position

the ballet's two principals

, but also has meanings relating to finance, law, and architecture. As an adjective, principal typically means "most important," as in

the principal reason.

principal

2 of 2

noun

prin·​ci·​pal ˈprin(t)-s(ə-)pəl 

-sə-bəl

1

: a person who has controlling authority or is in a leading position: such as

a

: a chief or head man or woman

b

: the chief executive officer of an educational institution

c

: one who engages another to act as an agent subject to general control and instruction

specifically : the person from whom an agent's authority derives

d

: the chief or an actual participant in a crime

e

: the person primarily or ultimately liable on a legal obligation

f

: a leading performer : star

2

: a matter or thing of primary importance: such as

a(1)

: a capital sum earning interest, due as a debt, or used as a fund

(2)

: the corpus of an estate, portion, devise, or bequest

b

: the construction that gives shape and strength to a roof and is usually one of several trusses

broadly : the most important member of a piece of framing

principalship

ˈprin(t)-s(ə-)pəl-ˌship 

-sə-bəl-

noun

Synonyms

Adjective

• arch
• big
• capital
• cardinal
• central
• chief
• dominant
• first
• foremost
• grand
• great
• greatest
• highest
• key
• leading
• main
• master
• number one
• No. 1
• numero uno
• overbearing
• overmastering
• overriding
• paramount
• predominant
• preeminent
• premier
• primal
• primary
• prior
• sovereign
• sovran
• supreme

Noun

• headliner
• lead
• star

Examples of principal in a Sentence

Adjective

If any suspect that Griswold was exaggerating, they should reflect on the fact that the principal Supreme Court case justifying the invocation of the national security privilege was based on a governmental lie. —Garry Wills, New York Review of Books, 12 Feb. 2009

Following the agreement, the four principal tobacco companies—Philip Morris, R. J. Reynolds, Brown & Williamson, and Lorillard—raised their prices more than 45 cents per pack. The costs of the settlement, as predicted, were passed on to consumers. —Allan M. Brandt, The Cigarette Century, 2007

Their principal industry was the manufacture, in a long, low, mostly-wooden, two-story factory, of cold cream. —Frederick Busch, Too Late American Boyhood Blues, 1984

Vegetables are the principal ingredients in this soup.

She is the principal cellist of the orchestra.

Noun

the new high school principal

One of the principals in the assassination plot has been arrested.

Recent Examples on the Web

Adjective

Zulauf has spent the past three years as principal at Community Consolidated District 59’s Rupley Elementary School in Elk Grove Village. —Chuck Fieldman, Chicago Tribune, 16 May 2025

Understanding that all investing involves risk including the loss of principal typical investors have some level of diversification outside of equities. —Letitia Berbaum, Forbes.com, 16 May 2025

Noun

A good number of Brooklyn’s neighborhoods boast those traits, says Timothy Quinlan, principal of Quinlan Development Group. —Jeffrey Steele, Forbes.com, 19 May 2025

Italy expects a lot from the red team, and the replacement of Mattia Binotto with Frédéric Vasseur as team principal was supposed to result in Maranello challenging for championships. —ArsTechnica, 19 May 2025

Word History

Etymology

Adjective and Noun

Middle English, from Anglo-French, from Latin principalis, from princip-, princeps

First Known Use

Adjective

14th century, in the meaning defined at sense 1

Noun

14th century, in the meaning defined at sense 1

Phrases Containing principal

• co-principal
• principal diagonal
• principal parts

Rhymes for principal

• principle

Kids Definition

principal

1 of 2 adjective

prin·​ci·​pal ˈprin(t)-s(ə-)pəl 

-sə-bəl

: most important : chief

the principal ingredient of the stew

principally

-ē 

prin(t)-splē

adverb

principal

2 of 2 noun

1

a

: a leading or most important person

b

: the head of a school

2

: a sum of money that is placed to earn interest, is owed as a debt, or is used as a fund

Legal Definition

principal

1 of 2 adjective

prin·​ci·​pal ˈprin-sə-pəl 

1

: being the main or most important, consequential, or influential

their principal place of business

the principal obligor

2

: of, relating to, or constituting principal or a principal

the principal amount of the loan

principal

2 of 2 noun

1

: a participant in an action or transaction especially having control or authority

the principals of a business

: as

a

: one who engages another to act for him or her subject to his or her general control or instruction : one from whom an agent derives authority to act compare fiduciary

b

: one who commits a crime or instigates, encourages, or assists another to commit it especially when constructively or actually present see also accessory sense 1

— principal in the first degree

: a principal under common law who intentionally commits and is actually or constructively present at the commission of a crime

— principal in the second degree

: a principal under common law who aids, encourages, or commands another to commit a crime and is actually or constructively present when it is committed

c

: the person primarily liable on a legal obligation or one who will ultimately bear the burden because of a duty to indemnify another as distinguished from one (as an endorser, surety, or guarantor) who is secondarily liable

2

: a capital sum earning interest, due as a debt, or used as a fund

shall receive the income from the trust until age 18, and thereafter the principal

payments shall be applied first to interest and then to principal

also : the main body of an estate, devise, or bequest