- faithless, traitorous, unfaithful - deliberately and abominably disloyal or likely to betray trust or confidence; "the faithless Benedict Arnold"; "a lying traitorous insurrectionist"
Antonym: loyal (indirect, via disloyal)
- traitorous, treasonable, treasonous - constituting treason; "a traitorous act"; "treasonable acts like sabotage"
Antonym: loyal (indirect, via disloyal)