The Collaborative International Dictionary of English v.0.48:
Meridian \Me*rid"i*an\, n. [F. m['e]ridien. See Meridian, a.]
1. Midday; noon.
2. Hence: The highest point, as of success, prosperity, or
the like; culmination.
I have touched the highest point of all my
And from that full meridian of my glory
I haste now to my setting. --Shak.
3. (Astron.) A great circle of the sphere passing through the
poles of the heavens and the zenith of a given place. It
is crossed by the sun at midday.
4. (Geog.) A great circle on the surface of the earth,
passing through the poles and any given place; also, the
half of such a circle included between the poles.
Note: The planes of the geographical and astronomical
meridians coincide. Meridians, on a map or globe, are
lines drawn at certain intervals due north and south,
or in the direction of the poles.
Calculated for the meridian of, or fitted to the meridian
of, or adapted to the meridian of, suited to the local
circumstances, capabilities, or special requirements of.
All other knowledge merely serves the concerns of
this life, and is fitted to the meridian thereof.
--Sir M. Hale.
First meridian or prime meridian, the meridian from which
longitudes are reckoned. The meridian of Greenwich is the
one commonly employed in calculations of longitude by
geographers, and in actual practice, although in various
countries other and different meridians, chiefly those
which pass through the capitals of the countries, are
occasionally used; as, in France, the meridian of Paris;
in the United States, the meridian of Washington, etc.
Guide meridian (Public Land Survey), a line, marked by
monuments, running North and South through a section of
country between other more carefully established meridians
called principal meridians, used for reference in
Magnetic meridian, a great circle, passing through the
zenith and coinciding in direction with the magnetic
needle, or a line on the earth's surface having the same
Meridian circle (Astron.), an instrument consisting of a
telescope attached to a large graduated circle and so
mounted that the telescope revolves like the transit
instrument in a meridian plane. By it the right ascension
and the declination of a star may be measured in a single
Meridian instrument (Astron.), any astronomical instrument
having a telescope that rotates in a meridian plane.
Meridian of a globe, or Brass meridian, a graduated
circular ring of brass, in which the artificial globe is
suspended and revolves.
The Collaborative International Dictionary of English v.0.48:
Circle \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,
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
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
That heavy bodies descend by gravity; and, again,
that gravity is a quality whereby a heavy body
descends, is an impertinent circle and teaches
10. Indirect form of words; circumlocution. [R.]
Has he given the lie,
In circle, or oblique, or semicircle. --J.
11. A territorial division or district.
The Circles of the Holy Roman Empire, ten in number, were
those principalities or provinces which had seats in the
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
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
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
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.