Green’s Dictionary of Slang

crazy, eccentric.

1836–7		Dickens Pickwick Papers (1999) 295: A stone statue of some rampacious animal with flowing mane and tail, distantly resembling an insane cart-horse.
1841		S.G. Goodrich Sketches from a Student’s Window 150: Then the feller becomes rampacious. He begs, and wheedles, and natters.
1855		New Mthly Mag. CV 249: Naughty roaring babies, dumb; rampacious boys, schooled into silence.
1865		K. Wood It May be True I 280: Miss Edith accused Carlo ; — you know what a rampacious dog he is.
1879		Croydon Advertiser 27 Dec. 4/6: As soon as [...] Mr Waddy is elected against the combined [...] influence of honest Tories and rampacious Roebuckites, the tone is changed.
1883		Leeds Times 21 July 6/6: The other three, making more noise than is exactly expected from ladies — in fact, as the landlady’s daughter commentred [...] ‘going on regular rampacious’.
1898		(con. 1875) F.T. Bullen Cruise of the ‘Cachalot’ 236: The bomb busted in his [i.e. a whale] belly [...] he went cleam rampageous loony.
1912		C.E. Gouldsbury Life in the Indian Police 33: Her Majesty the Queen-Emperor himself, who would no doubt (spelt dought) see with his own hand that such rampacious young police cub was given his desert.
1923		J. Manchon Le Slang.