(chemistry) Any of two or more compounds with the same molecular formula but with different structure.

plural of isomer

A surname. / A male given name; rare in English.

plural of Isom

(chemistry) Any of a number of compounds that exhibit structural isomerism

(chemistry, dated, deprecated by IUPAC) either the cis- or trans- isomer of a compound that exhibits geometric isomerism

(chemistry) Any one of a number of compounds that exhibit optical isomerism.

(chemistry) any isomer that differs from another isomer only in the position of a substituent, or of a double or triple bond

(physics) An excited state of an isotope, often having different a spin quantum number (designated with an m)

(chemistry) Any of a set of structural isomers that are related by a pericyclic reaction