epimerism (??p?m??r?z?m) n (Chemistry) optical isomerism in which isomers (epimers) can form about asymmetric atoms within the molecule, esp in carbohydrates[C20: German Epimer (see epi-, -mer) + -ism] epimeric adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014