1. Pertaining to, consisting of or involving treason; treacherous.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• reasonbable,
• resonable,
• repsonable,
• areasonable,
• reassonable,
• reasonaible,
• reasonble,
• reasonible,
• presonable,
• reasonnable,
• reasonablee,
• reasonabler,
• reasoonable,
• rasonable,
• rreasonable,
• reasonanble,
• reasinable,
• reasobnable,
• reasnable,
• reasoniable

• treasonably,
• treasonist,
• treasonous,
• True Senna,
• trigonal.

The adjective form of the word "treasonable" is "treasonous".

The plural form of the word "treasonable" is "treasonables".

The singular form of the word "treasonable" is "treasonable". The word does not change from its base form in the singular.