Definition of "gled"

I say that the eyass should have her meat unwashed, until she becomes a brancher—’twere the ready way to give her the frounce, to wash her meat sooner, and so knows every one who knows a gled from a falcon.

1820, [Walter Scott], chapter IV, in The Abbot. […], volume I, Edinburgh: […] [James Ballantyne & Co.] for Longman, Hurst, Rees, Orme, and Brown, […]; and for Archibald Constable and Company, and John Ballantyne, […], page 85

In this wise, the glossy bright-eyed kestrel, whom tiercels’ training could not reclaim, shook off silver bells, and velvet hood, and broidered jesses; and fled away—to consort, henceforward for evermore, with gleds, and hawks, and such birds of prey as make their nests deep in Bohemian forests, or in the desolate places of the Wilderness that girdles the frontier of the reputable world.

1866, [George Alfred Lawrence], “Evasit”, in Sans Merci; or, Kestrels and Falcons, volume III, London: Tinsley Brothers, […], page 126

“She’s sharp,” he said admiringly, nodding towards the screen, “she’s as sharp as a gled.”

1887 November 19, Leslie Keith, “Uncle Bob’s Niece”, in Charles Dickens [Jr.], editor, All the Year Round. A Weekly Journal., volume XLI, number 990, London: […], page 434, column 2