slate-grey vs slate-gray

slate-grey and slate-gray both are adjectives.

Word	Noun	Adjective	Verb	Adverb
slate-grey	No	Yes	No	No
slate-gray	No	Yes	No	No

As adjectives, slate-grey and slate-gray are synonyms defined as:

Other synonyms of slate-grey include slatey, slaty-gray, slaty-grey, slaty, stone-gray, stone-grey.

slate-grey (adjective)	slate-gray (adjective)
of the color of slate or granite	of the color of slate or granite