Green’s Dictionary of Slang

butterfly adj.

[butterfly n. (2)]

of clothes, gaudy, tasteless, flashy.

[UK]‘Doss Chiderdoss’ ‘Her New Game’ Sporting Times 29 Sept. 1/4: She was usually just a little ‘loud’ in her attire [...] But the other day a change came o’er the spirit of her dream, / For she threw aside her butterfly rig-out; / And apparelled in far better taste, she really looked the cream / Of society.