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.
The inefficacy was soon proved, like that of many similar medicines.
© Webster 1913.