Definition of "isomerism" [i•som•er•ism]

• The phenomenon of the existence of isomers. (noun)
• The complex of chemical and physical phenomena characteristic of or attributable to isomers. (noun)
• The state or condition of being an isomer. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The word isomerism was coined by Berzelius to express this anomalous condition of things, which seemed to negative the most fundamental truths of chemistry."
• "This phenomenon is called isomerism, and the generally accepted explanation is that the atoms in isomeric molecules are differently arranged, or grouped, in space."
• "Sometimes, Mrs. Janner, it is important to remember that life is an isomerism in which the isomers change into one another with great ease so that they ordinarily exist together in equilibrium."