grayish brown vs greyish brown

grayish brown and greyish brown both are nouns.

Word	Noun	Adjective	Verb	Adverb
grayish brown	Yes	No	No	No
greyish brown	Yes	No	No	No

As nouns, grayish brown and greyish brown are synonyms defined as:

grayish brown and greyish brown: a color or pigment varying around a light grey-brown color

Other synonyms of grayish brown include dun, fawn.

grayish brown (noun)	greyish brown (noun)
a color or pigment varying around a light grey-brown color	a color or pigment varying around a light grey-brown color