Source : Webster's Revised Unabridged Dictionary (1913)
Donkey \Don"key\, n.; pl. {Donkeys}. [Prob. dun, in allusion to
the color of the animal + a dim. termination.]
1. An ass; or (less frequently) a mule.
2. A stupid or obstinate fellow; an ass.
{Donkey engine}, a small auxiliary engine not used for
propelling, but for pumping water into the boilers,
raising heavy weights, and like purposes.
{Donkey pump}, a steam pump for feeding boilers,
extinguishing fire, etc.; -- usually an auxiliary.
{Donkey's eye} (Bot.), the large round seed of the {Mucuna
pruriens}, a tropical leguminous plant.