ef ‧ fi ‧ ca ‧ cy /ˈefəkəsi, ˈefɪkəsi/ BrE AmE noun [uncountable + of]
formal the ability of something to produce the right result SYN effectiveness OPP inefficacy
ef ‧ fi ‧ ca ‧ cy /ˈefəkəsi, ˈefɪkəsi/ BrE AmE noun [uncountable + of]
formal the ability of something to produce the right result SYN effectiveness OPP inefficacy
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012