Green’s Dictionary of Slang

breech n.

[citations are inconsistent as to the front or back pockets, although usage may simply have reversed over time from back to front]

(UK/US Und.) a trouser pocket.

Show quotations
[US]H. Hapgood Autobiog. of a Thief 129: I fell for a breech-kick (was arrested for picking a man’s trouser’s pocket).
[US]Jackson & Hellyer Vocab. Criminal Sl. 19: breech (britch) [...] The rear pants pockets, designated right and left breech, in contra-distinction to the front pants [...] Example: ‘Fan his right breech for a leather,’ i. e., ‘Feel of his right, hip pocket for a pocketbook’.
[UK]Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 1: Back breech: Back pocket.
[US](con. 1905–25) E.H. Sutherland Professional Thief (1956) 48: Special names are given to the pockets such as left or right breech (front trouser pocket), left or right prat (hip pocket), tail pit (side pocket), fob (under the belt), and insider (inside coat pocket). A left-breech tool is one who can steal from the left-front trouser pocket, which is unusually difficult.

In compounds