ˈjaˌkas, -kaa(ə)s, -kais also -kȧs in New Eng & Brit especially (in Brit at least) in sense 2 noun
Etymology: jack (I) + ass
1.
a. : a male ass ; also : donkey
b. Australia : kookaburra
2. : a stupid person : fool , dolt
a conceited jackass
3. : hawse bag