speak vs keynote

speak is not a noun while keynote is a noun.

Word	Noun	Adjective	Verb	Adverb
speak	No	No	Yes	No
keynote	Yes	No	Yes	No

As verbs, keynote is a hyponym of speak; that is, keynote is a word with a more specific, narrower meaning than speak:

Other hyponyms of speak include blaze away, memorialise, memorialize, harangue.

speak (noun)	keynote (noun)
	a fundamental or central idea
	(music) the first note of a diatonic scale
	the principal theme in a speech or literary work

speak (verb)	keynote (verb)
express in speech	set the keynote of
exchange thoughts; talk with	give the keynote address to (an audience)
use language
give a speech to
make a characteristic or natural sound