See quotations.
1834. Some, to whom it was not natural to do so, pushed out the under jaw, like a person who (to use a Southern term) is jimber-jawed.—Caruthers, ‘The Kentuckian in New-York,’ i. 195 (N.Y.). (Italics in the original.)
1848–60. Gimbal-jawed or jimber-jawed, whose lower jaw is loose and projecting (Bartlett).
1890. Word used in Philadelphia.—‘Dialect Notes,’ i. 74.
