po·lar /ˈpolɚ/ 形容詞
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.
Po·lar n. Conic Sections The right line drawn through the two points of contact of the two tangents drawn from a given point to a given conic section. The given point is called the pole of the line. If the given point lies within the curve so that the two tangents become imaginary, there is still a real polar line which does not meet the curve, but which possesses other properties of the polar. Thus the focus and directrix are pole and polar. There are also poles and polar curves to curves of higher degree than the second, and poles and polar planes to surfaces of the second degree.
adj 1: having a pair of equal and opposite charges
2: characterized by opposite extremes; completely opposed; "in
diametric contradiction to his claims"; "diametrical (or
opposite) points of view"; "opposite meanings"; "extreme
and indefensible polar positions" [syn: diametric, diametrical,
3: located at or near or coming from the earth's poles; "polar
diameter"; "polar zone"; "a polar air mass"; "Antarctica
is the only polar continent"
4: of or existing at or near a geographical pole or within the
Arctic or Antarctic Circles; "polar regions" [ant: equatorial]
5: extremely cold; "an arctic climate"; "a frigid day"; "gelid
waters of the North Atlantic"; "glacial winds"; "icy
hands"; "polar weather" [syn: arctic, frigid, gelid,
6: being of crucial importance; "a pivotal event"; "Its pivotal
location has also exposed it to periodic invasions"- Henry
Kissinger; "the polar events of this study"; "a polar
principal" [syn: pivotal]