obsolete Any general meeting place of dissenters of a given denomination of the (Christian) church; a conventicle. "Autem" is an obsolete slang word for church, and "cackletub" (a slang term for the pulpit of a church) here refers to a gather place of those who spill secrets ("cackle"). I entered into the autem cackletub with trepidation, for who knows what sort one may find in a place of unruly dissent.
See also: autem
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.