Principal

Part of speech: noun (n.)

1. A leader, chief, or head; one who takes the lead; one who acts independently, or who has controlling authority or influence; as, the principal of a faction, a school, a firm, etc.; -- distinguished from a subordinate, abettor, auxiliary, or assistant.

2. Hence: (Law)

3. The chief actor in a crime, or an abettor who is present at it, - - as distinguished from an accessory.

4. A chief obligor, promisor, or debtor, -- as distinguished from a surety.

5. One who employs another to act for him, -- as distinguished from an agent. Wharton. Bouvier. Burrill.

6. A thing of chief or prime importance; something fundamental or especially conspicuous. Specifically:

7. The first two long feathers of a hawk's wing. Spenser. J. H. Walsh.

8. One of turrets or pinnacles of waxwork and tapers with which the posts and center of a funeral hearse were formerly crowned. Oxf. Gloss.

9. A principal or essential point or rule; a principle. [Obs.]

Part of speech: adjective (a.)

1. Highest in rank, authority, character, importance, or degree; most considerable or important; chief; main; as, the principal officers of a Government; the principal men of a state; the principal productions of a country; the principal arguments in a case. Wisdom is the principal thing. Prov. iv. 7.

2. Of or pertaining to a prince; princely. [A Latinism] [Obs.] Spenser. Principal axis. See Axis of a curve, under Axis. -- Principal axes of a quadric (Geom.), three lines in which the principal planes of the solid intersect two and two, as in an ellipsoid. -- Principal challenge. (Law) See under Challenge. -- Principal plane. See Plane of projection (a), under Plane. -- Principal of a quadric (Geom.), three planes each of which is at right angles to the other two, and bisects all chords of the quadric perpendicular to the plane, as in an ellipsoid. -- Principal point (Persp.), the projection of the point of sight upon the plane of projection. -- Principal ray (Persp.), the line drawn through the point of sight perpendicular to the perspective plane. -- Principal section (Crystallog.), a plane passing through the optical axis of a crystal.