anchor vs mainstay

anchor and mainstay both are nouns.

Word	Noun	Adjective	Verb	Adverb
anchor	Yes	No	Yes	No
mainstay	Yes	No	No	No

As nouns, anchor and mainstay are synonyms defined as:

Other synonyms of anchor include backbone, keystone, linchpin, lynchpin.

anchor (noun)	mainstay (noun)
a mechanical device that prevents a vessel from moving	the forestay that braces the mainmast
a central cohesive source of support and stability	a central cohesive source of support and stability
a television reporter who coordinates a broadcast to which several correspondents contribute	a prominent supporter

anchor (verb)	mainstay (verb)
secure a vessel with an anchor
fix firmly and stably