hiss vs speak

hiss is a noun but speak is not a noun.

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

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

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

hiss (noun)	speak (noun)
a cry or noise made to express displeasure or contempt
a fricative sound (especially as an expression of disapproval)

hiss (verb)	speak (verb)
make a sharp hissing sound, as if to show disapproval	express in speech
express or utter with a hiss	exchange thoughts; talk with
show displeasure, as after a performance or speech	use language
move with a whooshing sound	give a speech to
	make a characteristic or natural sound