faithlessness vs inconstancy

faithlessness and inconstancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
faithlessness	Yes	No	No	No
inconstancy	Yes	No	No	No

As nouns, faithlessness and inconstancy are synonyms defined as:

faithlessness and inconstancy: unfaithfulness by virtue of being unreliable or treacherous

Other synonyms of faithlessness include falseness, fickleness.

faithlessness (noun)	inconstancy (noun)
unfaithfulness by virtue of being unreliable or treacherous	the quality of being changeable and variable
	unfaithfulness by virtue of being unreliable or treacherous