speed vs deceleration

speed and deceleration both are nouns.

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

As nouns, deceleration is a hyponym of speed; that is, deceleration is a word with a more specific, narrower meaning than speed:

Other hyponyms of speed include acceleration, quickening, speedup, scud, scudding.

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

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