treacherously vs faithlessly

treacherously and faithlessly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
treacherously	No	No	No	Yes
faithlessly	No	No	No	Yes

As adverbs, treacherously and faithlessly are synonyms defined as:

Other synonyms of treacherously include false, traitorously, treasonably.

treacherously (adverb)	faithlessly (adverb)
in a disloyal and faithless manner	in a disloyal and faithless manner