coastal vs seaward

coastal is not a noun while seaward is a noun.

Word	Noun	Adjective	Verb	Adverb
coastal	No	Yes	No	No
seaward	Yes	Yes	No	Yes

coastal (noun)	seaward (noun)
	the direction toward the sea

coastal (adjective)	seaward (adjective)
located on or near or bordering on a coast	(of winds) coming from the land
of or relating to a coast	directed or situated away from inland regions and toward the sea or coast
along or following a coast

coastal (adverb)	seaward (adverb)
	in the direction of the sea