ascendency vs ascendancy

ascendency and ascendancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
ascendency	Yes	No	No	No
ascendancy	Yes	No	No	No

As nouns, ascendency and ascendancy are synonyms defined as:

ascendency and ascendancy: the state that exists when one person or group has power over another

Other synonyms of ascendency include ascendance, ascendence, control, dominance.

ascendency (noun)	ascendancy (noun)
the state that exists when one person or group has power over another	the state that exists when one person or group has power over another