isomer

n. chemical compound which has the same number and kind of atoms as another but differs in structural arrangement (Chemistry)

In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of chemical bonds between atoms, but in which the atoms are arranged differently (analogous to a chemical anagram). Many isomers share similar if not identical properties in most chemical contexts. This should not be confused with a nuclear isomer, which involves a nucleus at different states of excitement.
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n. isomer, chemical compound which has the same number and kind of atoms as another but differs in structural arrangement (Chemistry)

adj. isomeric, of a chemical compound which has the same number and kind of atoms as another but differs in structural arrangement (Chemistry)

(n.)
A body or compound which is isomeric with another body or compound; a member of an isomeric series.
  

One of two or more compounds that have the same chemical formula but different arrangements of the atoms within the molecules and that may have different physical/chemical properties.