inefficacy

[ in-ef-i-kuh-see ]

/ ɪnˈɛf ɪ kə si /

lack of power or capacity to produce the desired effect.

Origin of inefficacy

From the Late Latin word inefficācia, dating back to 1605–15. See in-³, efficacy

They have long left off using the waters, after having experienced their inefficacy.

The Expedition of Humphry Clinker |Tobias Smollett
Gentlemen assign as a reason why the embargo should be removed, its inefficacy—that it has not answered the contemplated purpose.

Abridgement of the Debates of Congress, from 1789 to 1856 (4 of 16 vol.) |Various
Their inefficacy arises from the inutility of attempting to fix that which, like language, is essentially fluctuating.

The English Language |Robert Gordon Latham
But on that night he felt the inefficacy of conventional antidotes to melancholy.

The Trimmed Lamp |O. Henry

But he could even bring testimony to the inefficacy of such regulations.

The History of the Rise, Progress and Accomplishment of the |Thomas Clarkson