only 1 use
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Definition
effectiveness (the ability to produce a desired result)
- It is worthy of remark, as a curious physical instance of the efficacy of a sudden surprise in counteracting the effects of extreme fear, that her voice had quite recovered all its official asperity.Chapter 23 — Which Contains the Substance of a Pleasant Conversation.... (88% in)
There are no more uses of "efficacy" in Oliver Twist.
Typical Usage
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