What does enantiomeric mean?
Enantiomeric is an adjective used in chemistry to describe anything relating to enantiomers — pairs of molecules that share the same atoms and bonding but exist as mirror images of each other that cannot be superimposed, much like a person's left and right hands. Because living systems are themselves chiral, the two members of an enantiomeric pair can behave very differently biologically: one may be an effective medicine while its mirror image is inert or even harmful. The adjective therefore appears constantly in pharmaceutical and analytical contexts, most famously in the phrases 'enantiomeric excess' and 'enantiomeric purity', which measure how much of a chiral product consists of just one desired mirror-image form. Its opposite in spirit is 'racemic', describing an equal mixture of both forms.
adjectiveRelating to or consisting of enantiomers — a pair of molecules that are mirror images of each other and are non-superimposable. Used chiefly in chemistry to describe compounds, mixtures, forms, or properties that involve such mirror-image molecular structures.
- Of or relating to enantiomers; describing a compound, mixture, form, excess, or property that involves mirror-image, non-superimposable molecular structures.
"The drug was marketed as the single active enantiomeric form after researchers found its mirror-image twin caused harmful side effects."
"Chromatography separated the racemic mixture into its two enantiomeric components."
"The patent covered only the R-enantiomeric version of the compound, leaving the S-form to generic manufacturers."
The two enantiomeric forms of a molecule can smell, taste, and even heal or harm completely differently — your body can tell left from right at the molecular level.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of enantiomeric
Enantiomeric derives from 'enantiomer', a term built on the Greek adjective 'enantios', meaning 'opposite' or 'contrary'. Chemists coined 'enantiomer' in the late nineteenth century amid growing understanding of molecular chirality, combining the Greek root with '-mer', from 'meros', meaning 'part'. The same Greek root gives chemistry several related terms such as 'enantiomorphism' and 'enantioselective', all playing on the idea of opposition or mirror symmetry.
Related word forms
How enantiomeric is actually used
A technical term used almost exclusively in chemistry, pharmacology, and related sciences. It appears most often attributively before a noun (e.g., 'enantiomeric excess', 'enantiomeric purity'), which are standard measurements in chiral chemistry. Not used in everyday speech.
Easily confused with enantiomeric
Diastereomeric describes stereoisomers that are NOT mirror images of each other, whereas enantiomeric describes molecules that are exact non-superimposable mirror images.