Jack'ass` noun [ 2d jack + ass .] 1. The male ass; a donkey. 2. A conceited dolt; a perverse blockhead. Jackass bark (Nautical) , a three-masted vessel, with only the foremast square-rigged; a barkentine. -- Jackass deer (Zoology) , ... Found on http://www.encyclo.co.uk/webster/J/1