speed up vs speed

speed up is not a noun while speed is a noun.

Word	Noun	Adjective	Verb	Adverb
speed up	No	No	Yes	No
speed	Yes	No	Yes	No

As verbs, speed up and speed are synonyms defined as:

Other synonyms of speed up include accelerate, quicken.

As verbs, speed up and speed are synonyms defined as:

Other synonyms of speed up include accelerate.

speed up (noun)	speed (noun)
	changing location rapidly
	a central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression
	a rate (usually rapid) at which something happens
	the ratio of the focal length to the diameter of a (camera) lens system
	distance travelled per unit time

speed up (verb)	speed (verb)
move faster	move faster
cause to move faster	cause to move faster
	move very fast
	travel at an excessive or illegal velocity
	move hurridly