speed vs shoot down

speed is a noun but shoot down is not a noun.

Word	Noun	Adjective	Verb	Adverb
speed	Yes	No	Yes	No
shoot down	No	No	Yes	No

As verbs, shoot down is a hyponym of speed; that is, shoot down is a word with a more specific, narrower meaning than speed:

Other hyponyms of speed include barge, push forward, thrust ahead, buck, charge, shoot, tear, dart, dash, flash, scoot, scud, shoot.

speed (noun)	shoot down (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 (verb)	shoot down (verb)
move faster	shoot at and force to come down
cause to move faster	move quickly and violently
move very fast	thwart the passage of
travel at an excessive or illegal velocity
move hurridly