A character or person depicted has gray colored hair.
Whether using this tag is based purely off age or specific shades of gray different from silver has not been specified at this time.
Due to the subjective nature of color judgment and other factors (such as differences in color displayed on monitors) there is an overlap between this tag and the silver hair tag. There is also overlap between this tag and the blue hair and purple hair tags, generally in the lighter shades of those colors.
- Grey (Wikipedia article)
source: danbooru wiki