Short for JACK-BOOT. Ankle-jack: see ANKLE 3. colloq.
1801. C. K. Sharpe, Corr., 11 April (1888), I. 108. His lordship … wears … boots nearly approaching to jacks.
1869. Daily News, 13 July, 5/6. A short jacket and voluminous knickerbockers of light tweed, with purple worsted stockings, low-up ankle jacks, and a wide-awake hat.
