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polar cap

noun
1.
Geology. the icecap situated at either end of the earth's poles.
2.
Astronomy. either of the two bright areas around the poles of the planet Mars, consisting of water ice and frozen carbon dioxide.
Origin of polar cap
1890-1895
1890-95
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for polar cap
Historical Examples
  • The receptionist smiled icily at Tom, and then the smile vanished like a Martian polar cap.

    Get Out of Our Skies! E. K. Jarvis
  • It is said that no such line is visible during the formation of the polar cap with the approach of winter.

    Astronomy David Todd
  • As the Martian winter comes on in the northern34 hemisphere, for example, the polar cap extends its borders to the temperate zone.

    Mars and its Mystery Edward Sylvester Morse
polar cap in Science
polar cap  
  1. The mass of ice that covers either of the Earth's polar regions year-round.

  2. The mass of frozen carbon dioxide and water that covers either of Mars's polar regions.


The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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