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

Note: Do not confuse this word, principal, with the similar principle. Principle functions only as a noun and in its most common uses refers to a basic rule or law ("a guiding principle," "a matter of principle"). Note that if you are looking for an adjective form of principle, you must use principled ("taking a principled stand").

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

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 of principal

Adjective

• main
• primary
• greatest
• highest
• predominant
• foremost
• dominant
• chief

Noun

• 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

This will help your organization prioritize remediation efforts and focus on principal costs that directly impact current operations. —Daniel Kendzior, Fortune, 31 Oct. 2025

Apart from operating results, the quarter also saw the stunning resolution to a long-running family drama, as patriarch Rupert Murdoch reached a settlement designating his son, Lachlan, as principal heir to his media empire. —Dade Hayes, Deadline, 30 Oct. 2025

Noun

The principal didn’t immediately realize the alert had been canceled, a spokesperson for Baltimore County Public Schools told WBAL. —Karina Tsui, CNN Money, 25 Oct. 2025

Wilson was a constant presence at public forums and knew many principals and administrators on a first-name basis. —Drake Bentley, jsonline.com, 24 Oct. 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