What does diachylon mean?
Diachylon is the traditional name for a medicinal plaster once ubiquitous in Western pharmacy. Made by heating lead monoxide (litharge) with olive oil until they combine into a smooth, adhesive mass, it was spread on cloth or skin and applied to wounds, blisters, sprains, and inflamed areas to soothe and protect them. Known also as lead plaster, diachylon was a standard item in apothecaries from at least the medieval period well into the nineteenth century, and its name derives from Greek roots meaning roughly 'through juice,' a reference to its oily preparation. Because lead-based preparations are now recognized as hazardous, the term has fallen out of modern clinical use; it survives mainly in historical accounts of medicine, old formularies, and literary descriptions of earlier eras, where it evokes the domestic medical practices of past centuries.
nounA medicinal plaster prepared from lead monoxide and olive oil, formerly widely used in pharmacy as a soothing external application.
- A medicinal plaster made from lead monoxide (litharge) and olive oil, used externally to soothe and protect inflamed skin.
"The apothecary spread a thin layer of diachylon over the dressing before applying the bandage."
"Victorian pharmacists stocked diachylon alongside other household remedies for burns and chafing."
"She smoothed the warm diachylon onto a linen strip and applied it to the patient's blistered shoulder."
Rarely pluralized; the word usually functions as an uncountable mass noun referring to the substance itself.
"The shop's shelves held several jars of different diachylons, each mixed to its own recipe."
This unassuming plaster of lead and olive oil was a staple of the apothecary's shelf for centuries — and its name literally means 'through juice' in Greek.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diachylon
Diachylon comes from the Greek 'diachylōn', formed from 'dia-' ('through') and 'chylon' ('juice, sap'), referring originally to plant juices pressed out through expression. The word entered Latin as 'diachylon' and was adopted into European medical vocabulary, eventually narrowing to denote the lead-and-oil plaster familiar to later pharmacists. It shares its root 'chylo-' with English words such as 'chyle' and 'chylous', which likewise derive from the Greek term for juice.
How diachylon is actually used
An obsolete or historical term of pharmacy; today it appears chiefly in historical, medical-history, and literary contexts rather than in contemporary clinical practice.
Easily confused with diachylon
Diachrony/diachronic refers to change over time in language or history, whereas diachylon is a medicinal plaster made from lead and oil.