Meaning of -ACY in English
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.
[ -acia, -atia (sp. interchangeably in ML, reflecting the Rom merger of the forms); these are in turn complexes of - ac - and -at- -ATE 1 + - ia -Y 3 . Compare -CRACY ]
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012