The term used for the part of the soil that is permanently frozen in cold climates is "permafrost." Permafrost refers to soil, rock, or sediment that remains at or below 0 degrees Celsius (32 degrees Fahrenheit) for at least two consecutive years. It is typically found in regions with cold temperatures, such as Arctic and sub-Arctic areas. Permafrost can extend to considerable depths and has a significant impact on the landscape, ecosystems, and human activities in these regions.