Definition of "stereoisomerism"

(chemistry) A form of isomerism in which atoms are arranged differently about a chiral centre (or centre of asymmetry). They exhibit optical activity, and in a molecule with a single chiral centre the two isomers (enantiomers) are mirror images of each other whereas in a molecule with multiple chiral centres the isomers (diastereoisomers) are not normally mirror images.  examples