Found 2 items, similar to treasonably.
English → English (WordNet) Definition: treasonably treasonably adv : in a disloyal and faithless manner; “he behaved treacherously”; “his wife played him false” [syn: faithlessly, traitorously, treacherously, false]
English → English (gcide) Definition: Treasonably Treasonable \Trea"son*a*ble\, a. Pertaining to treason; consisting of treason; involving the crime of treason, or partaking of its guilt. [1913 Webster] Most men's heads had been intoxicated with imaginations of plots and treasonable practices. --Clarendon. [1913 Webster] Syn: Treacherous; traitorous; perfidious; insidious. [1913 Webster] --Trea"son*a*ble*ness, n. -- Trea"son*a*bly, adv. [1913 Webster]