Ass \Ass\, n. [OE. asse, AS. assa; akin to Icel. asni, W. asen, asyn, L. asinus, dim. aselus, Gr. ?; also to AS. esol, OHG. esil, G. esel, Goth. asilus, Dan. [ae]sel, Lith. asilas, Bohem. osel, Pol. osiel. The word is prob. of Semitic origin; cf. Heb. ath?n she ass. Cf. Ease.]

1. (Zo["o]l.) A quadruped of the genus Equus (E. asinus), smaller than the horse, and having a peculiarly harsh bray and long ears. The tame or domestic ass is patient, slow, and sure-footed, and has become the type of obstinacy and stupidity. There are several species of wild asses which are swift-footed.

2. A dull, heavy, stupid fellow; a dolt. --Shak.

Asses' Bridge. [L. pons asinorum.]

The fifth proposition of the first book of Euclid, ``The angles at the base of an isosceles triangle are equal to one another.'' [Sportive] ``A schoolboy, stammering out his Asses' Bridge.'' --F. Harrison.

To make an ass of one's self, to do or say something very foolish or absurd.

Source: Webster's Revised Unabridged Dictionary (1913)