a. 两极的, 极地的, 正好相反的, 极性的

n. 极线, 极面

[医] 极的

Polar \Po"lar\, a. [Cf. F. polaire. See {Pole} of the earth.]
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 co["o]rdinates.

{Polar axis}, that axis of an astronomical instrument, as an
equatorial, which is parallel to the earths axis.

{Polar bear} (Zo["o]l.), 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 spermatozo["o]n; 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[deg] 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[deg] from the sun.

{Polar co["o]rdinates}. See under 3d {Co["o]rdinate}.

{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
co["o]rdinates 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} (Zo["o]l.), 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} (Zo["o]l.), the right whale, or bowhead. See
{Whale}.


Polar \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.