What does eucalyptol mean?
Eucalyptol is a naturally occurring organic compound — specifically a monoterpene with the chemical formula C₁₀H₁₈O — that makes up the bulk of eucalyptus oil, typically accounting for the majority of its composition by volume. Also known by the alternative names cineole and cajeputol, it is a colourless liquid with a distinctive cool, camphor-like aroma reminiscent of the eucalyptus tree itself. Because of this penetrating scent and its mild medicinal properties, eucalyptol has long been valued in pharmaceutical products such as cough syrups, inhalants, lozenges, and topical rubs, where it acts as a flavouring, fragrance, and traditional expectorant. Beyond medicine, it finds application in flavouring confectionery, perfumery, and even as an insect repellent ingredient. The word derives from 'eucalyptus', the genus of Australian trees from which it was first isolated, combined with the chemical suffix '-ol' denoting an alcohol or similar oxygenated compound. While rarely heard in casual speech, eucalyptol is a staple term in chemistry, pharmacology, and aromatherapy circles.
nounA colourless, aromatic liquid monoterpene (C₁₀H₁₈O) that is the principal component of eucalyptus oil, used medicinally as an expectorant and flavouring agent. It is also known as cineole or cajeputol.
- A colourless, aromatic liquid terpene (C₁₀H₁₈O) that constitutes the main constituent of eucalyptus oil; also called cineole.
- A substance used in medicine as an expectorant, antiseptic, and flavouring agent.
"The cough syrup owes its cooling, camphor-like scent to eucalyptol distilled from eucalyptus leaves."
"The balm's distinctive fragrance comes from its high concentration of eucalyptol."
"Pharmacists once prized eucalyptol as a reliable expectorant for clearing congested airways."
Rarely pluralised, since the word denotes a single specific chemical compound. A plural form would only appear when referring to different samples, preparations, or sources of the compound.
"Laboratories may compare eucalyptols derived from different species of eucalyptus for purity."
Eucalyptol is the compound behind koalas' favourite meal — and your favourite cough drop.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of eucalyptol
Eucalyptol takes its name from 'eucalyptus', the tree genus from which it was first isolated, combined with the suffix '-ol' used in chemistry to denote alcohols and similar compounds. The word 'eucalyptus' itself comes from the Greek roots 'eu-' (meaning 'well' or 'good') and 'kalyptos' (meaning 'covered'), referring to the operculum that covers the flower bud before it opens — a feature noted when the genus was named in the late eighteenth century. Its alternative name 'cineole' derives ultimately from the Greek 'kineo' ('to move'), reflecting early chemical naming conventions.
How eucalyptol is actually used
A technical term used chiefly in chemistry, pharmacology, perfumery, and food-science contexts rather than everyday conversation. The synonym 'cineole' is equally common in scientific literature. British spelling of related descriptive terms follows '-ise' conventions; the word itself is identical in both varieties.
Easily confused with eucalyptol
Eucalyptus is the genus of trees themselves, while eucalyptol is the specific chemical compound extracted from their oil.