isomer

Any of two or more substances that have the same molecular formula but differ in their connectivity or spatial arrangement of atoms, or in their topology in macromolecules.

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.

In chem., a compound that exhibits the properties of isomerism with reference to some other compound. Also isomeride.

A compound which is isomeric with another body or compound; a compound having the same chemical composition as another compound; a member of an isomeric series.

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

Any of two or more atomic nuclei with the same mass number and atomic number but with different radioactive properties.

a compound that exists in forms having different arrangements of atoms but the same molecular weight