-ancy

1.
a combination of -ance and -y, used to form nouns denoting state or quality:
brilliancy.
Origin
< Latin -antia, equivalent to -ant- -ant (-ā- thematic vowel + -nt- present participle suffix) + -ia -y3
British Dictionary definitions for -ancy

-ance

suffix
1.
indicating an action, state or condition, or quality: hindrance, tenancy, resemblance Compare -ence
Word Origin
via Old French from Latin -antia; see -ancy

-ancy

suffix
1.
a variant of -ance, used to indicate condition or quality: expectancy, poignancy, malignancy
Word Origin and History for -ancy

word-forming element denoting quality or state, from Latin -antia, forming abstract nouns on pp. adjectives in -antem, appearing in English mostly in words borrowed directly from Latin (those passing through French usually have -ance or -ence; see -ance).