slack vs fall

slack and fall both are nouns.

Word	Noun	Adjective	Verb	Adverb
slack	Yes	Yes	Yes	No
fall	Yes	No	Yes	No

As verbs, fall is a hypernym of slack; that is, fall is a word with a broader meaning than slack:

Other hypernyms of slack include decrease, diminish, lessen.

slack (noun)	fall (noun)
a cord or rope or cable that is hanging loosely	a sudden drop from an upright position
the quality of being loose (not taut)	the act of surrendering (usually under agreed conditions)
a stretch of water without current or movement	a lapse into sin; a loss of innocence or of chastity
a soft wet area of low-lying land that sinks underfoot	a sudden sharp decrease in some quantity
a noticeable deterioration in performance or quality	a free and rapid descent by the force of gravity
dust consisting of a mixture of small coal fragments and coal dust and dirt that sifts out when coal is passed over a sieve	a sudden decline in strength or number or importance
	when a wrestler's shoulders are forced to the mat
	a movement downward
	a downward slope or bend
	the season when the leaves fall from the trees
	the time of day immediately following sunset

slack (adjective)	fall (adjective)
not tense or taut
lacking in rigor or strictness
flowing with little speed as e.g. at the turning of the tide

slack (verb)	fall (verb)
release tension on	occur at a specified time or place
make less active or fast	decrease in size, extent, or range
make less active or intense	pass suddenly and passively into a state of body or mind
become slow or slower	be born, used chiefly of lambs
cause to heat and crumble by treatment with water	come out; issue
become less in amount or intensity	assume a disappointed or sad expression
be inattentive to, or neglect	begin vigorously
avoid responsibilities and work, be idle	come as if by falling
	be cast down
	go as if by falling
	fall or flow in a certain way
	move downward and lower, but not necessarily all the way
	move in a specified direction
	descend in free fall under the influence of gravity
	slope downward
	drop oneself to a lower or less erect position
	lose an upright position suddenly
	to be given by assignment or distribution
	be captured
	fall to somebody by assignment or lot; passed
	come into the possession of
	to be given by right or inheritance
	be inherited by
	lose office or power
	yield to temptation or sin
	suffer defeat, failure, or ruin
	lose one's chastity
	die, as in battle or in a hunt
	be due
	come under, be classified or included
	touch or seem as if touching visually or audibly
	fall from clouds