What does "jackass" mean?

Jackass: A conceited dolt; a perverse blockhead. Jackass bark (Naut.), a three-masted vessel, with only the foremast square-rigged; a barkentine. -- Jackass deer (Zoöl.), the koba. -- Jackass hare, Jackass rabbit (Zoöl.). See Jack rabbit, under 2d Jack, n. -- Jackass penguin (Zoöl.), any species of penguin of the genus Spheniscus, of which several are known. One species (S. demersus) inhabits the islands near the Cape of Good Hope; another (S. Magellanicus) is found at the Falkland Islands. They make a noise like the braying of an ass; -- hence the name. -- Laughing jackass. (Zoöl.) See under Laughing.