Frigid Zone vs polar region

Frigid Zone and polar region both are nouns.

Word	Noun	Adjective	Verb	Adverb
Frigid Zone	Yes	No	No	No
polar region	Yes	No	No	No

As nouns, Frigid Zone and polar region are synonyms defined as:

Frigid Zone and polar region: the part of the Earth's surface forming a cap over a pole; characterized by frigid climate

Other synonyms of Frigid Zone include polar zone.

Frigid Zone (noun)	polar region (noun)
the part of the Earth's surface forming a cap over a pole; characterized by frigid climate	the part of the Earth's surface forming a cap over a pole; characterized by frigid climate