scythe vs cut down

scythe is a noun but cut down is not a noun.

Word	Noun	Adjective	Verb	Adverb
scythe	Yes	No	Yes	No
cut down	No	No	Yes	No

As verbs, cut down is a hypernym of scythe; that is, cut down is a word with a broader meaning than scythe:

Other hypernyms of scythe include mow.

scythe (noun)	cut down (noun)
an edge tool for cutting grass; has a long handle that must be held with both hands and a curved blade that moves parallel to the ground

scythe (verb)	cut down (verb)
cut with a scythe	cut down on; make a reduction in
	intercept (a player)
	cause to come or go down
	cut with a blade or mower
	cause to fall by or as if by delivering a blow
	cut with sweeping strokes; as with an ax or machete