It appears to originate in a 1919 novel about Abe Lincoln, A Man for the Ages.
Other datum:
More importantly in 1920, a new song was published: “At the New Jump Steady Ball.” This early Prohibition Era song uses “copasetic”—in the spelling identical to that in the novel—as the “password” to a speakeasy. “Copasetic was the password for one and all, At the new jump steady ball.”
'copasetic' looks out o' place to me.
It appears to originate in a 1919 novel about Abe Lincoln, A Man for the Ages.
Other datum:
https://languagelog.ldc.upenn.edu/nll/?p=31372
So it it a password.
Let’s use it on the released Wikileaks stuff.