isomer i·so·mer (ī'sə-mər)
Any of two or more substances that are composed of the same elements in the same proportions but differ in properties because of differences in the arrangement of atoms.
Any of two or more nuclei with the same mass number and atomic number that have different radioactive properties and can exist in any of several energy states for a measurable period of time.
|isomer (ī'sə-mər) Pronunciation Key
Any of two or more compounds, such as lactose and sucrose, composed of the same elements in the same proportions but differing in structure and other properties. There are two types of isomers, structural isomers and stereoisomers.