Definition of "donkey"

Lost last Saturday between twenty and thirty shillings they that have found it please to leave it heare there is five shillings reward by Wm. Roberts that goeth with a Donkey with many thanks

1776 August 24, “[untitled]”, in Ipswich Journal‎, Ipswich, Suffolk, page 1

DONKEY, donkey dick, a he, or jack ass, called donkey, perhaps from the Spanish, or don like gravity of that animal, entitled also the king of Spain's trumpeter

1785, Anonymous [Francis Grose], A Classical Dictionary of the Vulgar Tongue‎, London: S. Hooper

I vow we must be near the place from whereThe two converging slides, the avalanches,On Marshall, look like donkey's ears.We may as well see that and save the day.”“Don't donkey's ears suggest we shake our own?'For God's sake, aren't you fond of viewing nature? […]

2013 November 17, Robert Frost, Delphi Collected Works of Robert Frost (Illustrated) (Delphi Poets Series)‎, Delphi Classics

The chest may be found among those who stick to the sailing vessels, but for the steamer, the donkey died its natural death when the Suez Canal—responsible for many changes at sea—became an accomplished fact.

1903, W. H. Hood, The Blight of Insubordination‎, page 80