1.Definition: intermediate in character or position
"A grey area between clearly legal and strictly illegal"
2.Definition: of an achromatic color of any lightness intermediate between the extremes of white and black
"The little grey cells", "A man with greyish hair"
3.Definition: showing characteristics of age, especially having grey or white hair
4.Definition: used to signify the Confederate forces in the American Civil War (who wore grey uniforms)
"A stalwart grey figure"