mountains

As a noun mountains

is .

As an adjective undefined is

lacking a definition or value.

As an adjective highland

is relating to the highlands.

As a noun mountains is

.

As nouns the difference between foothills and mountains

is that foothills is while mountains is .

As nouns the difference between wetlands and mountains

is that wetlands is an area or region that is characteristically saturated; a marsh while mountains is .

As nouns the difference between mountains and jungle

is that mountains is while jungle is a large, undeveloped, humid forest, especially in a tropical region, that is home to many wild plants and animals.

As nouns the difference between mountains and terai

is that mountains is while terai is a belt of marshy land, which lies between the foothills of the himalayas and the plains.

As nouns the difference between mountains and glaciers

is that mountains is plural of lang=en while glaciers is plural of lang=en.

As nouns the difference between mountains and upland

is that mountains is while upland is the area in the interior of a country with a generally higher elevation; often hilly, but not generally mountainous (compare highlands).

As an adjective upland is

of, relating to, or situated in the uplands.

As nouns the difference between mountains and desert

is that mountains is while desert is desert.

As an adjective desert is

deserted.

As nouns the difference between forest and mountains

is that forest is a dense collection of trees covering a relatively large area. Larger than woods while mountains is plural of lang=en.

As a verb forest

is to cover an area with trees.