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.