donkeyish

Etymology
From.

Adjective

 * 1) Resembling or characteristic of a donkey; asinine.
 * 2) * 1885, "Two English Men of Letters" (uncredited), The Atlantic Monthly, Boston and New York: Houghton, Mifflin & Co., Volume 56, July, 1885, pp. 121-2,
 * He is concerned with his mental and spiritual growth, and so deeply interested in it is he that he is willing to spread upon the record the testimony of his memory to what can scarcely be regarded as less than donkeyish stupidity in youth.