—Usage note The noun principle and the noun and adjective principal are often confused. Although pronounced alike, the words are not interchangeable in writing. A principle is broadly “a rule of action or conduct” (His overriding principle is greed) or “a fundamental doctrine or tenet” (Their principles do not permit the use of alcoholic beverages). The adjective principal has the general sense “chief, first, foremost”: My principal objection is the cost of the project. The noun principal has among other meanings “the head or director of a school” (The faculty supported the principal in her negotiations with the board) and “a capital sum, as distinguished from interest or profit” (The monthly payments go mostly for interest, leaving the principal practically untouched).
First, highest, or foremost in importance, rank, worth, or degree; chief. See Synonyms at chief.
Of, relating to, or being financial principal, or a principal in a financial transaction.
n.
One who holds a position of presiding rank, especially the head of an elementary school or high school.
A main participant in a situation.
A person having a leading or starring role.
The capital or main body of an estate or financial holding as distinguished from the interest or revenue from it.
A sum of money owed as a debt, upon which interest is calculated.
A person who empowers another to act as his or her representative.
The person having prime responsibility for an obligation as distinguished from one who acts as surety or as an endorser.
One who commits or is an accomplice to a crime.
Law
A person who empowers another to act as his or her representative.
The person having prime responsibility for an obligation as distinguished from one who acts as surety or as an endorser.
One who commits or is an accomplice to a crime.
Architecture Either of a pair of inclined timbers forming the sides of a triangular truss for a pitched roof.
[Middle English, from Old French, from Latin prīncipālis, from prīnceps, prīncip-, leader, emperor; see per1 in Indo-European roots.]
prin'ci·pal·ly adv., prin'ci·pal·ship' n.
Usage Note: Principal and principle are often confused but have no meanings in common. Principle is only a noun and usually refers to a rule or standard. Principal is both a noun and an adjective. As a noun, it has specialized meanings in law and finance, but in general usage it refers to a person who holds a high position or plays an important role: a meeting among all the principals in the transaction. As an adjective it has the sense of "chief" or "leading": The coach's principal concern is the quarterback's health.
c.1290, from O.Fr. principal (11c.), from L. principalis "first in importance," from princeps (see prince). The noun is c.1300 in the sense of "ruler;" c.1340 in the sense of "money on which interest is paid;" 1827 as "person in charge of a public school," though meaning "head of a college or hall" was in England from 1438, and the basic sense of "chief, commander, ruler" is recorded from 1388. Principally "in the first place, mainly" is from 1340.
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"; "the master bedroom"; "a master switch" [syn: chief]
noun
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"
Fo"cus\, n.; pl. E. Focuses, L. Foci. [L. focus hearth, fireplace; perh. akin to E. bake. Cf. Curfew, Fuel, Fusil the firearm.]1. (Opt.) A point in which the rays of light meet, after being reflected or refrcted, and at which the image is formed; as, the focus of a lens or mirror. 2. (Geom.) A point so related to a conic section and certain straight line called the directrix that the ratio of the distace between any point of the curve and the focus to the distance of the same point from the directrix is constant. Note: Thus, in the ellipse FGHKLM, A is the focus and CD the directrix, when the ratios FA:FE, GA:GD, MA:MC, etc., are all equal. So in the hyperbola, A is the focus and CD the directrix when the ratio HA:HK is constant for all points of the curve; and in the parabola, A is the focus and CD the directrix when the ratio BA:BC is constant. In the ellipse this ratio is less than unity, in the parabola equal to unity, and in the hyperbola greater than unity. The ellipse and hyperbola have each two foci, and two corresponding directrixes, and the parabola has one focus and one directrix. In the ellipse the sum of the two lines from any point of the curve to the two foci is constant; that is: AG+GB=AH+HB; and in the hyperbola the difference of the corresponding lines is constant. The diameter which passes through the foci of the ellipse is the major axis. The diameter which being produced passes through the foci of the hyperbola is the transverse axis. The middle point of the major or the transverse axis is the center of the curve. Certain other curves, as the lemniscate and the Cartesian ovals, have points called foci, possessing properties similar to those of the foci of conic sections. In an ellipse, rays of light coming from one focus, and reflected from the curve, proceed in lines directed toward the other; in an hyperbola, in lines directed from the other; in a parabola, rays from the focus, after reflection at the curve, proceed in lines parallel to the axis. Thus rays from A in the ellipse are reflected to B; rays from A in the hyperbola are reflected toward L and M away from B. 3. A central point; a point of concentration. Aplanatic focus. (Opt.) See under Aplanatic. Conjugate focus (Opt.), the focus for rays which have a sensible divergence, as from a near object; -- so called because the positions of the object and its image are interchangeable. Focus tube (Phys.), a vacuum tube for R[oe]ntgen rays in which the cathode rays are focused upon the anticathode, for intensifying the effect. Principal, or Solar, focus (Opt.), the focus for parallel rays.
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. 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.
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