His books are enjoyable, but they don't do much to challenge the reader's 'gray matter'. [='intelligence']
His hair is 'graying'. = He has 'graying' hair.
What will you do when you are old and 'gray'?
(..) to your wedding? "Not basic." You know, not basic. I don't know how to explain it more than that. Yeah, like, Adam's wearing a gray suit. Mm, I mean, that's, like, semi-basic, but you guys are old. No one's looking at you anyways. I didn't know you were bringing Adam. (..)2017 TvShow: Superstore Title: Cheyenne's Wedding Season: 2 Episode 20