Meaning of jackass bark

jack'ass bark"

1. a barkentine square-rigged on the mainmast above a gaff mainsail.
2. Also calleda sailing ship having four or more masts, the foremast and mainmast being wholly square-rigged, the others being fore-and-aft-rigged.
3. any sailing ship of three or more masts carrying an otherwise nameless rig.