step on it vs hotfoot

step on it is not a noun while hotfoot is a noun.

Word	Noun	Adjective	Verb	Adverb
step on it	No	No	Yes	No
hotfoot	Yes	No	Yes	Yes

As verbs, step on it and hotfoot are synonyms defined as:

Other synonyms of step on it include belt along, bucket along, cannonball along, hasten, hie, pelt along, race, rush, rush along, speed.

step on it (noun)	hotfoot (noun)
	a practical joke that involves inserting a match surreptitiously between the sole and upper of the victim's shoe and then lighting it

step on it (verb)	hotfoot (verb)
move hurridly	move hurridly

step on it (adverb)	hotfoot (adverb)
	without delay; speedily