isopycnic

[ahy-suh-pik-nik]
noun
  1. a line drawn on a map connecting all points having the same density, as of water or air.

Origin of isopycnic

1885–90; iso- + pycnic, variant of pyknic
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018