numerical identity

noun
  1. logic the relation that holds between two relata when they are the selfsame entity, that is, when the terms designating them have the same referenceCompare qualitative identity See also Leibnitz's law
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012