set down vs light

set down is not a noun while light is a noun.

Word	Noun	Adjective	Verb	Adverb
set down	No	No	Yes	No
light	Yes	Yes	Yes	Yes

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

set down (noun)	light (noun)
	any device serving as a source of illumination
	a device for lighting or igniting fuel or charges or fires
	the visual effect of illumination on objects or scenes as created in pictures
	the quality of being luminous; emitting or reflecting light
	merriment expressed by a brightness or gleam or animation of countenance
	mental understanding as an enlightening experience
	a particular perspective or aspect of a situation
	public awareness
	a visual warning signal
	an illuminated area
	a person regarded very fondly
	(physics) electromagnetic radiation that can produce a visual sensation
	having abundant light or illumination
	a condition of spiritual awareness; divine illumination

set down (adjective)	light (adjective)
	of comparatively little physical weight or density
	psychologically light; especially free from sadness or troubles
	not great in degree or quantity or number
	of the military or industry; using (or being) relatively small or light arms or equipment
	(used of color) having a relatively small amount of coloring agent
	characterized by or emitting light
	(physics, chemistry) not having atomic weight greater than average
	of little intensity or power or force
	easily assimilated in the alimentary canal; not rich or heavily seasoned
	silly or trivial
	weak and likely to lose consciousness
	having little importance
	less than the correct or legal or full amount often deliberately so
	designed for ease of movement or to carry little weight
	moving easily and quickly; nimble
	(used of soil) loose and large-grained in consistency
	having relatively few calories
	(of sound or color) free from anything that dulls or dims
	(of sleep) easily disturbed
	marked by temperance in indulgence
	very thin and insubstantial
	casual and unrestrained in sexual behavior
	demanding little effort; not burdensome
	(used of vowels or syllables) pronounced with little or no stress
	intended primarily as entertainment; not serious or profound

set down (verb)	light (verb)
put down in writing; of texts, musical compositions, etc.	introduce light into
remove (cargo, people, etc.) from and leave	start or maintain a fire in
put or settle into a position	begin to smoke
cause to sit or seat or be in a settled position or place	to come to rest, settle
go ashore	alight from (a horse)
reach or come to rest	fall to somebody by assignment or lot; passed
	cause to start burning; subject to fire or great heat

set down (adverb)	light (adverb)
	with few burdens