from
The Collaborative International Dictionary of English v.0.48
Treacherous \Treach"er*ous\, a. [See {Treacher}.]
Like a traitor; involving treachery; violating allegiance or
faith pledged; traitorous to the state or sovereign;
perfidious in private life; betraying a trust; faithless.
[1913 Webster]
Loyal father of a treacherous son. --Shak.
[1913 Webster]
The treacherous smile, a mask for secret hate.
--Cowper.
[1913 Webster]
Syn: Faithless; perfidious; traitorous; false; insidious;
plotting.
[1913 Webster] -- {Treach"er*ous*ly}, adv. --
{Treach"er*ous*ness}, n.
[1913 Webster]