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Webster 1913 Edition

efficacy

ef′fi-ca-cy

,
Noun.
[L.
efficacia
, fr.
efficax
. See
Efficacious
.]
Power to produce effects; operation or energy of an agent or force; production of the effect intended;
as, the
efficacy
of medicine in counteracting disease; the
efficacy
of prayer.
“Of noxious efficacy.”
Milton.

Syn. – efficacy.
Syn. – Virtue; force; energy; potency; efficiency.

Webster 1828 Edition

Efficacy

EF'FICACY

,
Noun.
[L. efficax.] Power to produce effects;production to the effect intended; as the efficacy of the gospel in converting men from sin; the efficacy of prayer; the efficacy of medicine in counteracting disease; the efficacy of manure in fertilizing land.

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