diathermous envelope
diathermous envelope
[¦dī·ə¦thər·məs ′en·və‚lōp] (thermodynamics)
A surface enclosing a thermodynamic system in equilibrium that is not an adiabatic envelope; intuitively, this means that heat can flow through the surface.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.