n. [ L. inefficacia. See In- not, and Efficacy. ] Lack of power to produce the desired or proper effect; inefficiency; ineffectualness; futility; uselessness; fruitlessness;
The seeming inefficacy of censures. Bp. Hall. [ 1913 Webster ]
The inefficacy was soon proved, like that of many similar medicines. James Gregory. [ 1913 Webster ]