rhizoverbBeta
DictionarypermafrostPersistently frozen ground
noun

permafrost

PUR-muh-frawst/ˈpɜːrməfrɔːst/

Ground that remains frozen for at least two consecutive years.

In the Arctic, permafrost lies beneath a seasonally thawed surface layer.

Arctic tundra ground cutaway with deep permanently frozen soil and ice wedges beneath thin summer vegetation, no labels or arrows.
Etymology
permaEnglishlasting
+frostEnglishfreezing; frozen condition

Permanent frost names ground whose frozen condition persists year-round rather than disappearing with seasonal thaw. The emphasis is on lasting freezing, matching the requirement that the ground remain frozen across consecutive years.

In context

HISTORY19:19
The task became keeping the ground permanently frozen so that the foundations of what was built on the permafrost wouldn't sink and fall apart.
Modern Marvels: Journey into the World of Diamond Mining (S7, E51) | Full Episode | History

More examples

  • Permafrost stays frozen for at least two years in a row.
  • Thawing permafrost can damage roads and buildings.
  • Scientists drill into permafrost to study trapped organic material.