clack vs speak

clack is a noun but speak is not a noun.

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

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

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

clack (noun)	speak (noun)
a simple valve with a hinge on one side; allows fluid to flow in only one direction
a sharp abrupt noise as if two objects hit together; may be repeated

clack (verb)	speak (verb)
speak (about unimportant matters) rapidly and incessantly	express in speech
make a clucking sounds, characteristic of hens	exchange thoughts; talk with
make a rattling sound	use language
	give a speech to
	make a characteristic or natural sound