blue-chinned, adj. — Green’s Dictionary of Slang

blue-chinned adj.

[blue-chin n. and the fact that not shaving can make one’s chin look blue]

unshaven, usu. of actors.

1908		Sporting Times 15 Feb. 2/5: A blue-chinned super, out of work, looks at them with envy.
1932		W.R. Burnett Giant Swing 99: [H]e couldn’t help comparing his soft, olive, boyish face with Spanish’s, which was swarthy, blue-chinned, rough-cut.