The Law Dictionary

Your Free Online Legal Dictionary • Featuring Black’s Law Dictionary, 2nd Ed.

EFFICACY Definition & Legal Meaning

Definition & Citations:

1. Effectiveness. Likelihood of achieving desired end by expending effort. Example: Evaluate changes for their efficacy to produce desired result; if unsure the changes will do the job, reevaluate our plan. 2. Medicine: A treatment’s or vaccine’s effectiveness in curing, preventing, or lessening the effects of a disease or illness.


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