rant vs speak

rant is a noun but speak is not a noun.

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

As verbs, speak is a hypernym of rant; that is, speak is a word with a broader meaning than rant:

Other hypernyms of rant include mouth, talk, utter, verbalise, verbalize.

rant (noun)	speak (noun)
pompous or pretentious talk or writing
a loud bombastic declamation expressed with strong emotion

rant (verb)	speak (verb)
talk in a noisy, excited, or declamatory manner	express in speech
	exchange thoughts; talk with
	use language
	give a speech to
	make a characteristic or natural sound