principal

adj

1. Primary; most important; first level in importance.

   “Smith is the principal architect of this design.”

   “The principal cause of the failure was poor planning.”

   “In a word, the Epiſodes of Homer are complete Epiſodes; they are proper to the ſubject, because they are drawn from the ground of the fable; they are ſo joined to the principal action, that one is the neceſſary conſequence of the other, either truly or probably: and laſtly, they are imperfect members which do not make a complete and finiſhed body; for an Epiſode that makes a complete action, cannot be part of a principal action; as is eſſential to all Epiſodes.”

   “For many years, Oslo had no railway communication with Bergen and Stavanger, the principal seaports on the south-west coast.”

   “The principal treasure of ths department, however, is the Stele of Hammurabi (1792—1750 B.C.), king of the first Babylonian kingdom, a basalt cylinder 2.25m/7ft 5in. inscribed with Hammurabi's laws written in Akkadian in cuneiform script.”

2. (Latinism, obsolete)Of or relating to a prince; princely.

   “But walkt at will, and wandred to and fro, / In the pride of his freedome principall.”

3. Chosen or assumed among a branch of possible values of a multi-valued function so that the function is single-valued.

   “Two is the principal square root of 4. Both −2 and +2 are square roots of 4.”

noun

1. (uncountable)The money originally invested or loaned, on which basis interest and returns are calculated.

   “A portion of your mortgage payment goes to reduce the principal, and the rest covers interest.”

   “In March 1902, I find in the statement of liabilities and assets £711 put down as arrears of interest, but there is no entry of arrears of principal.”

   “2012, Denis Clifford, Plan Your Estate, 11th Edition, NOLO, US, page 298, For instance, in some states, dividends that have automatically been reinvested will be treated as principal.”

   “If you know the principal amount, the interest rate, and the number of years the payments will be made, you can consult an amortization calculator or schedule to arrive at the monthly payment.”

   “Coordinate term: interest”

2. (Australia, Canada, New-Zealand, Philippines, US, countable, uncountable)The chief administrator of a school.

   “The important administrative figure to the teacher is the school principal.”

   “The problem was neatly summed up by one principal in Australia who said recently: ‘There is no incentive for me to develop my best teachers to become my successor.[…]’”

   “Now renamed Teaching Australia, its officers are undertaking exploratory steps in developing professional standards for school leaders. A National Standards Drafting Group of volunteer principals is currently drafting principal standards (Teaching Australia, 2007).”

   “2011, U.S. Department of Labor, Occupational Outlook Handbook 2011-2012, page 45, Principals are now being held more accountable for the performance of students and teachers, while at the same time they are required to adhere to a growing number of government regulations.”

3. (Canada, UK, countable, uncountable)The chief executive and chief academic officer of a university or college.

   “1967, University of Edinburgh Graduates′ Association, University of Edinburgh Journal, Volumes 23-24, page 314, Unlike the students, Principal Robertson, who now resided almost alone in the College, continued to use the accustomed route on his visits to the Old Town; and it “became the joke of the day that from being the principal gate it had become only a gate for the Principal.”⁵”

   “Coordinate term: bursar”

4. (countable, uncountable)A legal person that authorizes another (the agent) to act on their behalf; or on whose behalf an agent or gestor in a negotiorum gestio acts.

   “When an attorney represents a client, the client is the principal who permits the attorney, the client′s agent, to act on the client′s behalf.”

   “My principal sells metal shims.”

   “The firm admitted the amount owed, but averred as an affirmative defense that it had hired the expert as an agent of a disclosed principal, the client.”

   “A food broker has been defined as an independent sales agent who performs the services of negotiating the sale of food and/or grocery products for and on account of the seller as principal.”

   “2009, California Continuing Education of the Bar, California Probate Code, page 375, An attorney-in-fact has a duty to act solely in yhe interest of the principal and to avoid conflicts of interest.”

5. (countable, uncountable)The primary participant in a crime.

   “The accessories may be prosecuted, tried and punished, though the principal has not been prosecuted or has been acquitted.”

6. (countable, uncountable)Either party in a duel.

   “The old man raised his arm as though it had been palsied, and fired, of course without effect. The other principal immediately deloped, much to the satisfaction of my friend and all present.”

7. (Canada, US, countable, uncountable)A partner or owner of a business.
8. (countable, uncountable)A type of stop on a pipe organ consisting of flue pipes with a bright tonal quality. They are also sometimes referred to as a diapason.
9. (countable, uncountable)The construction that gives shape and strength to a roof, generally a truss of timber or iron; or, loosely, the most important member of a piece of framing.
10. (countable, uncountable)The first two long feathers of a hawk's wing.

    “a birde whose principals be scarce growne out”

    “The first two feathers - Principals”

11. (countable, uncountable)One of the turrets or pinnacles of waxwork and tapers with which the posts and centre of a funeral hearse were formerly crowned
12. (countable, obsolete, uncountable)An essential point or rule; a 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.”

13. (countable, uncountable)A dancer at the highest rank within a professional dance company, particularly a ballet company.
14. (countable, uncountable)A security principal.
15. (countable, uncountable)A main character or lead actor.

    “Silverberg also gives the reader reader some excellent character insight; deep probes into the minds of all the principals bring the reader closer to the persons involved than might be thought possible with the plot so far removed from the realm of normality.”