DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   jnd
       n 1: (psychophysics) the difference between two stimuli that
            (under properly controlled experimental conditions) is
            detected as often as it is undetected [syn: just-
    noticeable difference, jnd]