INEF'FICACY, n. [in and efficacy, L. efficacia.] 1. Want of power to produce the desired or proper effect; inefficiency; as the inefficacy of medicines or of means. 2. Ineffectualness; failure of effect.
Inefficacy In*ef"fi*ca*cy, n. [L. inefficacia. See In- not, and Efficacy.] Want of power to produce the desired or proper effect; inefficiency; ineffectualness; futility; uselessness; fruitlessness; as, the inefficacy of medicines or means. The seeming inefficacy of censures. --Bp. Hall. The inefficacy was soon proved, like that of many similar medicines. --James Gregory.