flirt vs speak

flirt is a noun but speak is not a noun.

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

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

Other hypernyms of flirt include talk.

flirt (noun)	speak (noun)
playful behavior intended to arouse sexual interest
a seductive woman who uses her sex appeal to exploit men

flirt (verb)	speak (verb)
talk or behave amorously, without serious intentions	express in speech
behave carelessly or indifferently	exchange thoughts; talk with
	use language
	give a speech to
	make a characteristic or natural sound