\Cir"cle\ (s[~e]r"k'l), n. [OE. cercle, F. cercle, fr. L.
circulus (Whence also AS. circul), dim. of circus circle,
akin to Gr. kri`kos, ki`rkos, circle, ring. Cf. {Circus},
{Circum-}.]
1. A plane figure, bounded by a single curve line called its
   circumference, every part of which is equally distant from
   a point within it, called the center.
2. The line that bounds such a figure; a circumference; a
   ring.
3. (Astron.) An instrument of observation, the graduated limb
   of which consists of an entire circle.
Note: When it is fixed to a wall in an observatory, it is
      called a {mural circle}; when mounted with a telescope
      on an axis and in Y's, in the plane of the meridian, a
      {meridian or transit circle}; when involving the
      principle of reflection, like the sextant, a
      {reflecting circle}; and when that of repeating an
      angle several times continuously along the graduated
      limb, a {repeating circle}.
4. A round body; a sphere; an orb.
         It is he that sitteth upon the circle of the earth.
                                               --Is. xi. 22.
5. Compass; circuit; inclosure.
         In the circle of this forest.         --Shak.
6. A company assembled, or conceived to assemble, about a
   central point of interest, or bound by a common tie; a
   class or division of society; a coterie; a set.
         As his name gradually became known, the circle of
         his acquaintance widened.             --Macaulay.
7. A circular group of persons; a ring.
8. A series ending where it begins, and repeating itself.
         Thus in a circle runs the peasant's pain. --Dryden.
9. (Logic) A form of argument in which two or more unproved
   statements are used to prove each other; inconclusive
   reasoning.
         That heavy bodies descend by gravity; and, again,
         that gravity is a quality whereby a heavy body
         descends, is an impertinent circle and teaches
         nothing.                              --Glanvill.
10. Indirect form of words; circumlocution. [R.]
          Has he given the lie, In circle, or oblique, or
          semicircle.                          --J. Fletcher.
11. A territorial division or district.
Note:
{The Circles of the Holy Roman Empire}, ten in number, were
   those principalities or provinces which had seats in the
   German Diet.
{Azimuth circle}. See under {Azimuth}.
{Circle of altitude} (Astron.), a circle parallel to the
   horizon, having its pole in the zenith; an almucantar.
{Circle of curvature}. See {Osculating circle of a curve}
   (Below).
{Circle of declination}. See under {Declination}.
{Circle of latitude}.
    (a) (Astron.) A great circle perpendicular to the plane
        of the ecliptic, passing through its poles.
    (b) (Spherical Projection) A small circle of the sphere
        whose plane is perpendicular to the axis.
{Circles of longitude}, lesser circles parallel to the
   ecliptic, diminishing as they recede from it.
{Circle of perpetual apparition}, at any given place, the
   boundary of that space around the elevated pole, within
   which the stars never set. Its distance from the pole is
   equal to the latitude of the place.
{Circle of perpetual occultation}, at any given place, the
   boundary of the space around the depressed pole, within
   which the stars never rise.
{Circle of the sphere}, a circle upon the surface of the
   sphere, called a great circle when its plane passes
   through the center of the sphere; in all other cases, a
   small circle.
{Diurnal circle}. See under {Diurnal}.
{Dress circle}, a gallery in a theater, generally the one
   containing the prominent and more expensive seats.
{Druidical circles} (Eng. Antiq.), a popular name for certain
   ancient inclosures formed by rude stones circularly
   arranged, as at Stonehenge, near Salisbury.
{Family circle}, a gallery in a theater, usually one
   containing inexpensive seats.
{Horary circles} (Dialing), the lines on dials which show the
   hours.
{Osculating circle of a curve} (Geom.), the circle which
   touches the curve at some point in the curve, and close to
   the point more nearly coincides with the curve than any
   other circle. This circle is used as a measure of the
   curvature of the curve at the point, and hence is called
   circle of curvature.
{Pitch circle}. See under {Pitch}.
{Vertical circle}, an azimuth circle.
{Voltaic} {circle or circuit}. See under {Circuit}.
{To square the circle}. See under {Square}.
Syn: Ring; circlet; compass; circuit; inclosure.

\Cir"cle\, v. t. [imp. & p. p. {Circled}; p. pr. & vb. n.
{Circling}.] [OE. cerclen, F. cercler, fr. L. circulare to
make round. See {Circle}, n., and cf. {Circulate}.]
1. To move around; to revolve around.
         Other planets circle other suns.      --Pope.
2. To encompass, as by a circle; to surround; to inclose; to
   encircle. --Prior. Pope.
         Their heads are circled with a short turban.
                                               --Dampier.
         So he lies, circled with evil.        --Coleridge.
{To circle in}, to confine; to hem in; to keep together; as,
   to circle bodies in. --Sir K. Digby.

\Cir"cle\, v. i.
To move circularly; to form a circle; to circulate.
      Thy name shall circle round the gaping through.
                                               --Byron.