Isomer (noun)

1. A compound with the same chemical formula as another but with a different arrangement of atoms in its molecule.
2. A molecule that has the same chemical formula as another molecule but has a different arrangement of atoms.

Origin:

From the greek "isos" meaning "equal" and "meros" meaning "part", coined in 1875 by german chemist carl somiesky.

Examples:

1. There are two isomers of butane, n-butane and isobutane.
2. The pharmaceutical industry heavily relies on the study of isomers to develop new drugs.
3. The different isomers of glucose have different effects on the body.
4. Isomers are important in organic chemistry as they can have vastly different properties and reactivity.
5. The isomers of cyclohexane have different stability.