a suffix of nouns of quality, state, office, etc., many of which accompany adjectives in -acious or nouns or adjectives in -ate: fallacy; papacy; legacy; delicacy; piracy.
Origin of
-acy
< Latin
-ācia,-ātia (spelling interchangeably in Medieval Latin, reflecting the Rom merger of the forms); these are in turn complexes of
-āc- and
-āt--ate1 +
-ia-y3. Cf.
-cracy
