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permafrost Line breaks: perma|frost
Pronunciation: /ˈpəːməfrɒst/

Definition of permafrost in English:


[mass noun]
A thick subsurface layer of soil that remains below freezing point throughout the year, occurring chiefly in polar regions: hilly terrain underlain by permafrost
More example sentences
  • The permafrost below the topsoil is frozen all year around, and this prevents roots from penetrating deeply into the ground.
  • In regions influenced by permafrost, water migrates along the thermal gradient from warm to cold, thereby feeding ice in the frozen core.
  • In many high mountains regions, permafrost may be present.


1940s: from permanent + frost.

Definition of permafrost in:
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