From WordNet (r) 2.0 (August 2003) [wn]:
principal
adj : most important element; "the chief aim of living"; "the main
doors were of solid glass"; "the principal rivers of
America"; "the principal example"; "policemen were
primary targets" [syn: {chief(a)}, {main(a)},
{primary(a)}, {principal(a)}]
n 1: the original amount of a debt on which interest is
calculated
2: the educator who has executive authority for a school; "she
sent unruly pupils to see the principal" [syn: {school
principal}, head teacher, head]
3: an actor who plays a principal role [syn: star, lead]
4: capital as contrasted with the income derived from it [syn:
corpus, principal sum]
5: the major party to a financial transaction at a stock
exchange; buys and sells for his own account [syn:
dealer]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Principal \Prin"ci*pal\, 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.
[1913 Webster]
2. Hence: (Law)
(a) The chief actor in a crime, or an abettor who is
present at it, -- as distinguished from an accessory.
(b) A chief obligor, promisor, or debtor, -- as
distinguished from a surety.
(c) One who employs another to act for him, -- as
distinguished from an agent. --Wharton. --Bouvier.
--Burrill.
[1913 Webster]
3. A thing of chief or prime importance; something
fundamental or especially conspicuous. Specifically:
(a) (Com.) A capital sum of money, placed out at interest,
due as a debt or used as a fund; -- so called in
distinction from interest or profit.
(b) (Arch. & Engin.) The construction which gives shape
and strength to a roof, -- generally a truss of timber
or iron, but there are roofs with stone principals.
Also, loosely, the most important member of a piece of
framing.
(c) (Mus.) In English organs the chief open metallic stop,
an octave above the open diapason. On the manual it is
four feet long, on the pedal eight feet. In Germany
this term corresponds to the English open diapason.
(d) (O. Eng. Law) A heirloom; a mortuary. --Cowell.
(e) pl. The first two long feathers of a hawk's wing.
--Spenser. --J. H. Walsh.
(f) One of turrets or pinnacles of waxwork and tapers with
which the posts and center of a funeral hearse were
formerly crowned. --Oxf. Gloss.
(g) A principal or essential point or rule; a principle.
[Obs.]
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Principal \Prin"ci*pal\, a. [F., from L. principalis. See
Prince.]
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.
[1913 Webster]
Wisdom is the principal thing. --Prov. iv. 7.
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2. Of or pertaining to a prince; princely. [A Latinism]
[Obs.] --Spenser.
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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.
[1913 Webster]