Unbreech \Un*breech"\, v. t. [imp. & p. p. {Unbreeched}; p. pr. & vb. n. {Unbreching}.] [1st pref. un- + breech.] 1. To remove the breeches of; to divest or strip of breeches. --Shak. 2. (Gun.) To free the breech of, as a cannon, from its fastenings or coverings. --Pennant.