main vs hydrosphere

main and hydrosphere both are nouns.

Word	Noun	Adjective	Verb	Adverb
main	Yes	Yes	No	No
hydrosphere	Yes	No	No	No

main (noun)	hydrosphere (noun)
a principal pipe in a system that distributes water or gas or electricity or that collects sewage	the watery layer of the earth's surface; includes water vapor
any very large body of (salt) water

main (adjective)	hydrosphere (adjective)
(of a clause) capable of standing syntactically alone as a complete sentence
most important element
of force; of the greatest possible intensity