Green’s Dictionary of Slang

scat v.¹

to leave, to go away, esp. as a command.

1844		J.C. Neal Peter Ploddy and Other Oddities 8: She did not say ‘scat’ – she knew it was Pete, in the dark.
1855		T. Haliburton Nature and Human Nature I 116: Skat, skat, you nasty devil, you.
1866		G.W. Harris ‘Sut Lovingood’s Big Dinner Story’ Nashville Union and American XXXIII Aug. in Inge (1967) 168: Sez I, ‘skat,’ an’ he skated instuntly.
1881		J.C. Harris Uncle Remus 83: W’en ole man Rabbit say ‘scoot,’ dey scooted, en w’en ole Miss Rabbit say ‘scat,’ dey scatted.
1889		Dead Bird (Sydney) 23 Nov. 2/4: The point of a cotton umbrella was thrust from the window, followed by the pious injunction, ‘Scat, you grey-headed wretch!’ He ‘scatted’.
1892		National Observer 20 Aug. 356/1: They could be induced to ‘dismiss’ only by an impassioned cry of ‘scat-up!’ [F&H].
1896		J.F. Lillard Poker Stories 210: We chucked him two watches and $380 in cash quick’n scat.
1907		Sun. Times (Perth) 4 Aug. 3s/5: Before you could say ‘S’cat,’ the black-and-red was lying on its back.
1909		Gem 23 Jan. 7: ‘Scat!’ said the rancher unceremoniously, and Buck Finn ‘scatted’.
1918		Van Loan Fore! 179: Shoo! Scat! Mush on! Vamose! Beat it! Hurry up! Wiki-wiki! Chop-chop! Schnell!
1926		Boys’ Realm 16 Jan. 265: ‘Now, scat!’ snapped Evans.
1928		J. Callahan Man’s Grim Justice 89: They might raise their windows and [...] shout ‘skat’ at me.
1931		D. Runyon ‘Lillian’ in Guys and Dolls (1956) 235: She will leap aboard them quicker than you can say scat.
1941		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 10 May 9/5: I’m a trifle fat, and find it hard to scat.
1943		W. Guthrie Bound for Glory (1969) 417: Beat it! Skat!
1946		Mezzrow & Wolfe Really the Blues 246: G’wan, you didn’t pay no room rent around here, scat!
1950		C. Harris Three-Ha’Pence to the Angel 219: Gor on, scat!
1957		Kerouac On The Road (1972) 249: The time was coming to scat off to Mexico.
1962		(con. WWII) J.O. Killens And Then We Heard The Thunder (1964) 279: Scat! Scat! Everybody tryna get into the act.
1968		H. Sackler Great White Hope I vii: Why she scat off den, wid her man in trouble?
1973		C. Gaines Stay Hungry 214: He shoulda [...] scatted his ass out of there.
1973		H. Leonard Da (1981) Act I: Hoosh. Scat. Out.
1975		(con. 1900s) G. Swarthout Shootist 41: When my roomers find out who he is, they’ll leave like scat.
2000		F. Mac Anna Cartoon City 102: ‘Don’t ever let me see your mug again,’ the man said. ‘Go on, scat.’.

In phrases

get scat of (v.)

to get rid of.

1891

F.W. Carew Autobiog. of a Gipsey 416: There were nothink to be done but get scat of the lot.