Green’s Dictionary of Slang

1. a goatee beard.

1842		Whip & Satirist of NY & Brooklyn (NY) 25 June n.p.: One of them sports a very tasty pair of whiskers [...] the other has what is termed a ‘goat’ or whiskers under the chin.
1857		S.G. Goodrich Recollections I 210: His special admirers saw great merit in [...] his long shaggy goat.
1876		J.S. Ingram Centennial Express v 151: The little, puckered-mouth, pug-nosed, Esquimaux, with his slight sprinkling of a moustache and ‘goat,’ was also exhibited [DA].
1997–2000		Da Bomb 🌐 13: Goat: Short for goatee.
2019		D. Winslow Border [ebook] Hair cut short, had him a mustache and a small goat.

2. a scapegoat.

1913		B.T. Harvey ‘Word-List From The Northwest’ in DN IV:i 26: goat, n. One who has to stand the blame.
1926		M. West Sex (1997) Act II: She’s trying to make me the goat.
1931		W.N. Burns One-Way Ride 310: When the police are too dumb to solve a crime, I’m always somewhere in the background as the brains of the job. I’m the official goat of the Chicago police department.
1948		T. Thursday ‘Movie Stuff’ in Detective Story Apr. 🌐 You must be crazy! [...] What are you trying to do, make me the goat?
1953		R. Chandler Long Good-Bye 290: ‘I hate the idea of your being the goat. You tried so hard to do the right thing – as you saw it.’ ‘Nice of you,’ I said. ‘If I stick my neck out and it gets chopped, it’s still my neck.’.
1982		(con. 1970) J. Ehrlichman Witness to Power 99: Hickel had begun as the goat of the Cabinet. The media had savaged him.