leeward vs downwind

leeward is a noun but downwind is not a noun.

Word	Noun	Adjective	Verb	Adverb
leeward	Yes	Yes	No	Yes
downwind	No	Yes	No	Yes

leeward (noun)	downwind (noun)
the side of something that is sheltered from the wind
the direction in which the wind is blowing

leeward (adjective)	downwind (adjective)
on the side away from the wind	towards the side away from the wind

leeward (adverb)	downwind (adverb)
away from the wind	with the wind; in the direction the wind is blowing
	toward the wind