English
efficacy
Efficacy comes from Late Latin efficāx ‘efficacious’, from Latin efficiō ‘to make out, work out’, and ultimately from Proto-Indo-European *dʰeh₁k-.
- Proto-Indo-Europeanc. 4500–2500 BCE*dʰeh₁k-reconstructed
- Proto-Indo-European, derivedc. 4500–2500 BCE*dʰh₁kyétireconstructed
- Proto-Italicc. 1500–700 BCE*θakjōreconstructed
- Proto-Italic, derivedc. 1500–700 BCE*fakjō‘to make’reconstructed
- Latinc. 75 BCE–200 CEfaciō‘to make, construct, fashion, frame, build, erect’
- Latin, derivedc. 75 BCE–200 CEefficiō‘to make out, work out’
- Late Latinc. 200–600 CEefficāx‘efficacious’
- Late Latin, derivedc. 200–600 CEefficācia
- Old Frenchc. 842–1400efficace
- Englishearliest quotation 1642efficacy
attested reconstructed ? uncertain or disputed
Lineage
- Proto-Indo-Europeanc. 4500–2500 BCE*dʰeh₁k-reconstructed
- Proto-Indo-European, derivedc. 4500–2500 BCE*dʰh₁kyétireconstructed
- Proto-Italicc. 1500–700 BCE*θakjōreconstructed
- Proto-Italic, derivedc. 1500–700 BCE*fakjō‘to make’reconstructed
- Latinc. 75 BCE–200 CEfaciō‘to make, construct, fashion, frame, build, erect’
- Latin, derivedc. 75 BCE–200 CEefficiō‘to make out, work out’
- Late Latinc. 200–600 CEefficāx‘efficacious’
- Late Latin, derivedc. 200–600 CEefficācia
- Old Frenchc. 842–1400efficace
- Englishearliest quotation 1642efficacy
Earliest quotation: 1642, Sir Thomas Browne, Religio Medici [The Religion of a Doctor]: “[…]and this hath even made me ſuſpect the efficacy…”
Formed from -acy
Linked words
through Proto-Italic *θakjō
affectionate, imperfection, putrefaction, 65 more
through Proto-Italic *fakjō ‘to make’
factor, effectively, perfection, interface, difficulty, manufacture, effectiveness, affection, faction, imperfect, ineffective, facet, affective, defection, defector, confectionary, affectation, deface, 68 more
through Latin faciō ‘to make, construct, fashion, frame, build, erect’
face, perfect, fact, feature, difficult, effective, profit, facility, affect, infection, faculty, affair, feat, facial, facilitate, sacrifice, fetish, deficit, defect, counterfeit, infect, superficial, facade, façade, deficient, facsimile, hacienda, beautify, confection, parfait, maleficent, aficionado, effector, facies, refectory, confit, difficile, beneficent, 86 more
through Latin efficiō ‘to make out, work out’
Today it means
noun The ability to produce a desired effect under ideal testing conditions.
Language periods are conventional ranges, not dates for this word.
Etymograph / Proto-Indo-European *dʰeh₁k- / efficacy