Pronunciation: (prin'su-pul),[key] —adj. 1. first or highest in rank, importance, value, etc.; chief; foremost.
2. of, of the nature of, or constituting principal or capital: a principal investment. 3. Geom.(of an axis of a conic) passing through the foci.
—n. 1. a chief or head.
2. the head or director of a school or, esp. in England, a college.
3. a person who takes a leading part in any activity, as a play; chief actor or doer.
4. the first player of a division of instruments in an orchestra (excepting the leader of the first violins).
5. something of principal or chief importance.
6. Law. a. a person who authorizes another, as an agent, to represent him or her.
b. a person directly responsible for a crime, either as an actual perpetrator or as an abettor present at its commission. Cf. accessory (def. 3).
7. a person primarily liable for an obligation, in contrast with an endorser, or the like.
8. the main body of an estate, or the like, as distinguished from income.
9. Finance.a capital sum, as distinguished from interest or profit.
10. Music. a. an organ stop.
b. the subject of a fugue.
11. (in a framed structure) a member, as a truss, upon which adjacent or similar members depend for support or reinforcement.
12. each of the combatants in a duel, as distinguished from the seconds.