1) Futility 2) Ineffectiveness 3) Ineffectuality 4) Ineffectualness 5) Inefficaciousness 1) Inefficaciousness 2) Inutility 
• (n.) Want of power to produce the desired or proper effect; inefficiency; ineffectualness; futility; uselessness; fruitlessness; as, the inefficacy of medicines or means.
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) ... Origin: L. Inefficacia. See In- not, and Eff...
In·ef'fi·ca·cy noun [ Latin 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
[n] - a lack of efficacy
inefficaciousness noun a lack of efficacy
lack of power or capacity to produce the desired effect.