tread vs copulate

tread is a noun but copulate is not a noun.

Word	Noun	Adjective	Verb	Adverb
tread	Yes	No	Yes	No
copulate	No	No	Yes	No

As verbs, copulate is a hypernym of tread; that is, copulate is a word with a broader meaning than tread:

Other hypernyms of tread include couple, mate, pair.

tread (noun)	copulate (noun)
a step in walking or running
structural member consisting of the horizontal part of a stair or step
the part (as of a wheel or shoe) that makes contact with the ground
the grooved surface of a pneumatic tire

tread (verb)	copulate (verb)
crush as if by treading on	engage in sexual intercourse
brace (an archer's bow) by pressing the foot against the center
mate with (used of male birds)
tread or stomp heavily or roughly
put down or press the foot, place the foot
apply (the tread) to a tire