flat-footed vs splayfoot

flat-footed is not a noun while splayfoot is a noun.

Word	Noun	Adjective	Verb	Adverb
flat-footed	No	Yes	No	No
splayfoot	Yes	Yes	No	No

flat-footed (noun)	splayfoot (noun)
	a foot afflicted with a fallen arch; abnormally flattened and spread out

flat-footed (adjective)	splayfoot (adjective)
forthright and explicit	having feet that turn outward
with feet flat on the ground; not tiptoe
having broad flat feet that usually turn outward
unprepared and unable to react quickly