Inefficacy definitions

Webster's 1828 Dictionary

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.

WordNet (r) 3.0 (2005)

n
1: a lack of efficacy [syn: inefficacy, inefficaciousness] [ant: efficaciousness, efficacy]

Merriam Webster's

noun Etymology: Late Latin inefficacia, from Latin inefficac-, inefficax inefficacious, from in- + efficac-, efficax efficacious Date: circa 1615 lack of power to produce a desired effect

Webster's 1913 Dictionary

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.

Soule's Dictionary of English Synonyms

n. Ineffectualness.