Webster's English Dictionary

Enter the word to look up:

isomerism

isom.er.ism \i--'sa:m-*-.riz-*m\ n 1: the relation of two or more chemical 
   compounds, radicals, or ions that c ontain the same number of atoms of the 
   same elements but differ in structural arrangement and properties 2: the 
   relation of two or more nuclides with the same mass numbers and atom ic 
   numbers but different energy states and rates of radioactive decay 3: the 
   condition of being isomerous