adjective

1. first in rank, authority, importance, degree, etc.
2. that is or has to do with principal ()

Etymology: OFr < L principalis < princeps: see prince

noun

1. a principal person or thing; specif.,
   1. a chief; head
   2. a governing or presiding officer, specif. of a school
   3. a main actor or performer
   4. either of the combatants in a duel
2. 1. any of the main end rafters of a roof, supporting the purlins
   2. a roof truss
3. Finance
   1. the amount of a debt, investment, etc. minus the interest, or on which interest is computed
   2. the face value of a stock or bond
   3. the main body of an estate, etc., as distinguished from income
4. Law
   1. a person who employs another to act as his agent
   2. the person primarily responsible for an obligation
   3. a person who commits a crime or is present as an abettor to it
5. Music
   1. any of the principal open stops of an organ
   2. the soloist in a concert
   3. the first player of any section of orchestral instruments except the first violins
   4. the subject of a fugue