subtitle vs furnish

subtitle is a noun but furnish is not a noun.

Word	Noun	Adjective	Verb	Adverb
subtitle	Yes	No	Yes	No
furnish	No	No	Yes	No

As verbs, furnish is a hypernym of subtitle; that is, furnish is a word with a broader meaning than subtitle:

Other hypernyms of subtitle include offer, provide, render, supply.

subtitle (noun)	furnish (noun)
secondary or explanatory title
translation of foreign dialogue of a movie or TV program; usually displayed at the bottom of the screen

subtitle (verb)	furnish (verb)
supply (a movie) with subtitles	give something useful or necessary to
	provide or equip with furniture