[in.ef.fi.ca.cy] n [LL inefficacia, fr. L inefficac-, inefficax inefficacious, fr. in- + efficac-, efficax efficacious] (ca. 1615): lack of power to produce a desired effect
INEFFICACY
Meaning of INEFFICACY in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012