Trea"son*a*ble (?), a. Pertaining to
treason; consisting of treason; involving the crime of treason, or
partaking of its guilt.
Most men's heads had been intoxicated with imaginations of
plots and treasonable practices.
Clarendon.
Syn. -- Treacherous; traitorous; perfidious; insidious.
--Trea"son*a*ble*ness, n. --
Trea"son*a*bly, adv.