Himalaya vs Himalayas

Himalaya and Himalayas both are nouns.

Word	Noun	Adjective	Verb	Adverb
Himalaya	Yes	No	No	No
Himalayas	Yes	No	No	No

As nouns, Himalaya and Himalayas are synonyms defined as:

Himalaya and Himalayas: a mountain range extending 1500 miles on the border between India and Tibet; this range contains the world's highest mountain

Other synonyms of Himalaya include Himalaya Mountains.

Himalaya (noun)	Himalayas (noun)
a mountain range extending 1500 miles on the border between India and Tibet; this range contains the world's highest mountain	a mountain range extending 1500 miles on the border between India and Tibet; this range contains the world's highest mountain