Grizzled describes hair that has gone grey in streaks and patches — not all dark, not all white, but mixed. A grizzled beard, a grizzled head, the grizzled face of an old dog. The picture is worn by years. Though actually, writers often push it a little further. A grizzled detective or a grizzled coach may be there as much for the years on them as for the exact colour of their hair. The word is putting age and hard experience on a person. You will meet it in stories and newspapers more than in chat. It is not a rude word, but it does say “not young,” so you would not usually say it to someone’s face unless you were sure they would smile. It does not mean fully grey. Fully grey is just grey. Grizzled is the mix.