Definition of "gaby"

I daresay I made a gaby of myself to the world

1860 January–June, W[illiam] M[akepeace] Thackeray, chapter 1, in Lovel the Widower, London: Smith, Elder and Co., […], published 1861

"[Y]ou're a jobbernowl and a doodle, a maundering mooncalf and a blockheaded numps, a gaby and a loon; you're a Hatter!" I shrieked the last epithet.

1902, John Kendrick Bangs, chapter 10, in Olympian Nights

"You pair of gabeys!" she exclaimed. "You'll see him before the night's out."

1913, D[avid] H[erbert] Lawrence, “chapter 2”, in Sons and Lovers, London: Duckworth & Co. […]