slur vs speak

slur is a noun but speak is not a noun.

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

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

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

slur (noun)	speak (noun)
a blemish made by dirt
a disparaging remark
(music) a curved line spanning notes that are to be played legato

slur (verb)	speak (verb)
become vague or indistinct	express in speech
utter indistinctly	exchange thoughts; talk with
speak disparagingly of; e.g., make a racial slur	use language
play smoothly or legato	give a speech to
	make a characteristic or natural sound