DICT.TW Dictionary Taiwan

 Po·lar a.
 1. Of or pertaining to one of the poles of the earth, or of a sphere; situated near, or proceeding from, one of the poles; as, polar regions; polar seas; polar winds.
 2. Of or pertaining to the magnetic pole, or to the point to which the magnetic needle is directed.
 3. Geom. Pertaining to, reckoned from, or having a common radiating point; as, polar coordinates.
 Polar axis, that axis of an astronomical instrument, as an equatorial, which is parallel to the earths axis.
 Polar bear Zool., a large bear (Ursus maritimus syn. Thalarctos maritimus) inhabiting the arctic regions.  It sometimes measures nearly nine feet in length and weighs 1,600 pounds.  It is partially amphibious, very powerful, and the most carnivorous of all the bears.  The fur is white, tinged with yellow.  Called also White bear. See Bear.
 Polar body, Polar cell, or Polar globule Biol., a minute cell which separates by karyokinesis from the ovum during its maturation.  In the maturation of ordinary ova two polar bodies are formed, but in parthogenetic ova only one.  The first polar body formed is usually larger than the second one, and often divides into two after its separation from the ovum.  Each of the polar bodies removes maternal chromatin from the ovum to make room for the chromatin of the fertilizing spermatozoon; but their functions are not fully understood.
 Polar circles Astron. & Geog., two circles, each at a distance from a pole of the earth equal to the obliquity of the ecliptic, or about 23° 28´, the northern called the arctic circle, and the southern the antarctic circle.
 Polar clock, a tube, containing a polarizing apparatus, turning on an axis parallel to that of the earth, and indicating the hour of the day on an hour circle, by being turned toward the plane of maximum polarization of the light of the sky, which is always 90° from the sun.
 Polar coordinates. See under 3d Coordinate.
 Polar dial, a dial whose plane is parallel to a great circle passing through the poles of the earth. --Math. Dict.
 Polar distance, the angular distance of any point on a sphere from one of its poles, particularly of a heavenly body from the north pole of the heavens.
 Polar equation of a line or Polar equation of a surface, an equation which expresses the relation between the polar coordinates of every point of the line or surface.
 Polar forces Physics, forces that are developed and act in pairs, with opposite tendencies or properties in the two elements, as magnetism, electricity, etc.
 Polar hare Zool., a large hare of Arctic America (Lepus arcticus), which turns pure white in winter.  It is probably a variety of the common European hare (Lepus timidus).
 Polar lights, the aurora borealis or australis.
 Polar opposition, or Polaric opposition or Polar contrast or Polaric contrast Logic, an opposition or contrast made by the existence of two opposite conceptions which are the extremes in a species, as white and black in colors; hence, as great an opposition or contrast as possible.
 Polar projection. See under Projection.
 Polar spherical triangle Spherics, a spherical triangle whose three angular points are poles of the sides of a given triangle. See 4th Pole, 2.
 Polar whale Zool., the right whale, or bowhead. See Whale.

 Pro·jec·tion n.
 1. The act of throwing or shooting forward.
 2. A jutting out; also, a part jutting out, as of a building; an extension beyond something else.
 3. The act of scheming or planning; also, that which is planned; contrivance; design; plan.
 4. Persp. The representation of something; delineation; plan; especially, the representation of any object on a perspective plane, or such a delineation as would result were the chief points of the object thrown forward upon the plane, each in the direction of a line drawn through it from a given point of sight, or central point; as, the projection of a sphere. The several kinds of projection differ according to the assumed point of sight and plane of projection in each.
 5. Geog. Any method of representing the surface of the earth upon a plane.
 Conical projection, a mode of representing the sphere, the spherical surface being projected upon the surface of a cone tangent to the sphere, the point of sight being at the center of the sphere.
 Cylindric projection, a mode of representing the sphere, the spherical surface being projected upon the surface of a cylinder touching the sphere, the point of sight being at the center of the sphere.
 Globular, Gnomonic, Orthographic, projection,etc. See under Globular, Gnomonic, etc.
 Mercator's projection, a mode of representing the sphere in which the meridians are drawn parallel to each other, and the parallels of latitude are straight lines whose distance from each other increases with their distance from the equator, so that at all places the degrees of latitude and longitude have to each other the same ratio as on the sphere itself.
 Oblique projection, a projection made by parallel lines drawn from every point of a figure and meeting the plane of projection obliquely.
 Polar projection, a projection of the sphere in which the point of sight is at the center, and the plane of projection passes through one of the polar circles.
 Powder of projection Alchemy., a certain powder cast into a crucible or other vessel containing prepared metal or other matter which is to be thereby transmuted into gold.
 Projection of a point on a plane Descriptive Geom., the foot of a perpendicular to the plane drawn through the point.
 Projection of a straight line of a plane, the straight line of the plane connecting the feet of the perpendiculars let fall from the extremities of the given line.
 Syn: -- See Protuberance.
 ◄ ►