faithlessly

Từ điển WordNet v3.1 - WordNet Dictionary

adverb

in a disloyal and faithless manner
- he behaved treacherously
- his wife played him false
• Syn:
traitorously, treacherously, treasonably, false
• Derived from adjective:
treasonable (for: treasonably), treacherous (for: treacherously), traitorous (for: traitorously), faithless