Definition of polar in English:

polar

Line breaks: polar
Pronunciation: /ˈpəʊlə
 
/

adjective

  • 1Relating to the North or South Pole: the polar regions
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    • It warns of adverse consequences such as the melting of glaciers and polar icecaps, leading to rising sea levels.
    • And also things like what's happening to the glaciers and the different mountain regions or the polar ice caps or ocean temperatures.
    • Glaciers, permafrost and polar ice caps are melting, and droughts, floods and more extreme storms are occurring more frequently in many parts of the world.
    Synonyms
  • 1.1(Of an animal or plant) living in the north or south polar region: most polar birds breed seasonally
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    • They were found alongside the remains of mammoth, reindeer and polar fox, and they appear to have been eaten by their human masters.
    • But populations of frogs, butterflies, ocean corals, and polar birds have already gone extinct because of climate change, Parmesan said.
    • But polar species are far fewer in number and may not face the same extinction risk as those that live in more confined hot spots with greater biodiversity.
  • 1.2 Astronomy Relating to the poles of a celestial body: the polar radius of Jupiter is 66,550 km
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    • This means that its equatorial radius would be 40 kilometers greater than the polar radius.
    • Scientists will also dig into the puzzling asymmetry in the Sun's magnetism that was discovered by Ulysses during the first polar passes.
    • Also there are areas at higher elevation on the rim of polar craters that see the Sun more than half of the time.
  • 1.3 Astronomy Relating to a celestial pole.
  • 1.4 Geometry Relating to the poles of a sphere. See pole2.
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    • The Earth is an oblate spheroid, with polar diameter some 45 km less than the equatorial diameter.
  • 1.5 Biology Relating to the poles of a cell, organ, or part.
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    • The most utilized fluorescent markers of dead cells are polar DNA-binding dyes, unable to penetrate intact plasma membranes.
    • Class 1 mutations (b and c) elongate cells and cause predominantly polar bud site selection.
    • Angiosperm seeds are comprised of an embryo and endosperm resulting from double fertilization of the egg cell and two polar nuclei, respectively.
  • 2 Physics & Chemistry Having electrical or magnetic polarity.
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    • Another active area of biophysical research concerns the study of the interactions involving charged, polar and polarizable groups of atoms in proteins.
    • For example, HCl comprised of the atom Hydrogen and Chlorine is polar.
    • It is polar, that is the oxygen atom has a negative electrical charge while the two hydrogen atoms are positive.
  • 2.1(Of a liquid, especially a solvent) consisting of molecules with a dipole moment.
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    • With sodium chloride and water, the saturated condition is rapidly reached because the attraction between the sodium chloride ions and the polar water molecules is so strong.
    • In addition, the growth of coatings containing higher levels of solids such as epoxy resins, polyesters and urethanes has increased the demand for polar solvents such as ethyl acetate.
    • Recent work in our laboratory has explored the clustering behaviour of organic polar solvents such as methanol, 6 ethanol and butanol.
  • 2.2(Of a solid) ionic.
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    • The compound lithium hydride, LiH, is a polar covalent solid that reacts with water to liberate hydrogen gas and form basic solutions of the metal hydroxide.
    • The C-Cl bond is polar covalent, Na-Cl is ionic, and the C-C bond is pure covalent with each atom sharing the bonding electrons equally.
    • In addition, the dipolar water molecules are supposed to be strongly bound to ionic and polar parts along the protein surface.

noun

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  • 1 Geometry The straight line joining the two points at which tangents from a fixed point touch a conic section.
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    • Sturm's theoretical work in mathematical physics involved the study of caustic curves, and poles and polars of conic sections.
    • This exactly means that the directrix is the polar of the focus, while the focus is the pole of the directrix with respect to the parabola.
    • Bobillier is best known for his work on polars of curves and of algebraic surfaces.
  • 2 Astronomy A variable binary star which emits strongly polarized light, one component being a strongly magnetic white dwarf.

Origin

mid 16th century: from medieval Latin polaris 'heavenly', from Latin polus 'end of an axis' (see pole2).

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