spice up vs salt

spice up is not a noun while salt is a noun.

Word	Noun	Adjective	Verb	Adverb
spice up	No	No	Yes	No
salt	Yes	Yes	Yes	No

As verbs, salt is a hyponym of spice up; that is, salt is a word with a more specific, narrower meaning than spice up:

spice up (noun)	salt (noun)
	the taste experience when common salt is taken into the mouth
	white crystalline form of especially sodium chloride used to season and preserve food
	a compound formed by replacing hydrogen in an acid by a metal (or a radical that acts like a metal)

spice up (adjective)	salt (adjective)
	(of speech) painful or bitter

spice up (verb)	salt (verb)
make more interesting or flavorful	preserve with salt
add herbs or spices to	add zest or liveliness to
	sprinkle as if with salt
	add salt to