term:

Principal

principal adj

1 : being the main or most important, consequential, or influential [their place of business] [the obligor]
2 : of, relating to, or constituting principal or a principal [the amount of the loan]
n 1 : a participant in an action or transaction esp. having control or authority [the s 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 esp. when constructively or actually present see also accessory

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 ] [payments shall be applied first to interest and then to ]
;also
: the main body of an estate, devise, or bequest

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.