Cir·cle n.
 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  circle 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 circuit or Voltaic circle. See under Circuit.
 To square the circle. See under Square.
 Syn: -- Ring; circlet; compass; circuit; inclosure.
 Cir·cuit n.
 1. The act of moving or revolving around, or as in a circle or orbit; a revolution; as, the periodical circuit of the earth round the sun.
 2. The circumference of, or distance round, any space; the measure of a line round an area.
    The circuit or compass of Ireland is 1,800 miles.   --J. Stow.
 3. That which encircles anything, as a ring or crown.
    The golden circuit on my head.   --Shak.
 4. The space inclosed within a circle, or within limits.
    A circuit wide inclosed with goodliest trees.   --Milton.
 5. A regular or appointed journeying from place to place in the exercise of one's calling, as of a judge, or a preacher.
 6. (a) Law A certain division of a state or country, established by law for a judge or judges to visit, for the administration of justice. --Bouvier. (b) Methodist Church A district in which an itinerant preacher labors.
 7. Circumlocution. [Obs.] “Thou hast used no circuit of words.”
 Circuit court Law, a court which sits successively in different places in its circuit (see Circuit, 6). In the United States, the federal circuit courts are commonly presided over by a judge of the supreme court, or a special circuit judge, together with the judge of the district court. They have jurisdiction within statutory limits, both in law and equity, in matters of federal cognizance. Some of the individual States also have circuit courts, which have general statutory jurisdiction of the same class, in matters of State cognizance.
 Circuit of action or Circuity of action Law, a longer course of proceedings than is necessary to attain the object in view.
 To make a circuit, to go around; to go a roundabout way.
 Voltaic circle or Galvanic circle or Voltaic circuit or Galvanic circuit, a continous electrical communication between the two poles of a battery; an arrangement of voltaic elements or couples with proper conductors, by which a continuous current of electricity is established.