Efficacy

Part of speech: noun

Pronunciation: /ˈɛf.ɪ.kə.si/

Definitions

1. The degree to which an action or treatment can produce the desired results is known as its measure of potency
2. The capacity of something to achieve the intended effect or result
3. The ability of an agent or method to bring about a successful outcome

Etymology: "Efficacy" is a noun that descends from the Latin verb "facere," meaning "to make" or "to do," and its ancestry runs through a chain of Latin prefixes and suffixes. The Latin "efficere" combined "ex-" ("out") with "facere," giving the sense "to work out" or "to accomplish." From that verb came the adjective "efficax," meaning able to produce a result, and from it the Late Latin noun "efficacia." That noun passed into Old French as "efficace," the adjective, and from there the English noun "efficacy" took shape. Its ending comes from the English suffix "-acy," which in this word simply keeps the Latin noun's ending, so "efficacy" is essentially a Latin noun that arrived in English by way of French. The core idea is still visible: efficacy is the power to make something happen, carried over from the old Latin sense of getting a task done.

Synonyms: effectiveness, efficiency, potency, success, capability

Antonyms: ineffectiveness, inefficiency, failure, inability, weakness