A saddle. “Vaulting ambition ... o'erleaps its sell” (Macbeth, i. 7). (Latin, sella; French, selle.) Window sill is the Anglo-Saxon syl (a basement).
“He left his loftie steed with golden sell.”
Spenser: Faërie Queene, ii. 2.
Sell, sold. Made a captive, as a purchased slave. St. Paul says he was “sold under sin” (Rom. vii. 14), (Anglo-Saxon, sell-an, to give.)
A sell. A “do,” a deception, a “takein.” Street vendors who take in the unwary with catchpennies, chuckle like hens when they have laid an egg, “Sold again, and got the money!”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894