isorropic line

from The Collaborative International Dictionary of English v.0.48

Isorropic \I`sor*rop"ic\, a. [Gr. 'iso`rropos in equipoise;
   'i`sos equal + "roph` downward inclination or momentum.]
   Of equal value.
   [1913 Webster]

   {Isorropic line} (in a diagram) (Geom.), the locus of all the
      points for which a specified function has a constant
      value. --Newcomb.
      [1913 Webster]