diff --git a/include/neutral_parallel_diffusion.hxx b/include/neutral_parallel_diffusion.hxx
index 47af5312..71b2fea2 100644
--- a/include/neutral_parallel_diffusion.hxx
+++ b/include/neutral_parallel_diffusion.hxx
@@ -41,12 +41,12 @@ struct NeutralParallelDiffusion : public Component {
       .doc("Fix correcting pressure advection and conductivity factors?")
       .withDefault<bool>(true);
 
-    thermal_conduction = options["thermal_conducton"]
-      .doc("Enable conduction?")
+    perpendicular_conduction = options["perpendicular_conduction"]
+      .doc("Enable parallel projection of perpendicular conduction?")
       .withDefault<bool>(true);
 
-    viscosity = options["viscosity"]
-      .doc("Enable viscosity?")
+    perpendicular_viscosity = options["perpendicular_viscosity"]
+      .doc("Enable parallel projection of perpendicular viscosity?")
       .withDefault<bool>(true);
   }
 
@@ -80,8 +80,8 @@ private:
   std::string diffusion_collisions_mode;  ///< Collision selection, either afn or legacy
   Field3D nu;   ///< Collision frequency for conduction
   bool equation_fix;  ///< Fix incorrect 3/2 factor in pressure advection?
-  bool thermal_conduction; ///< Enable conduction?
-  bool viscosity; ///< Enable viscosity?
+  bool perpendicular_conduction; ///< Enable conduction?
+  bool perpendicular_viscosity; ///< Enable viscosity?
 
   /// Per-species diagnostics
   struct Diagnostics {
diff --git a/src/neutral_parallel_diffusion.cxx b/src/neutral_parallel_diffusion.cxx
index 457dd237..f8f1c4c6 100644
--- a/src/neutral_parallel_diffusion.cxx
+++ b/src/neutral_parallel_diffusion.cxx
@@ -115,13 +115,13 @@ void NeutralParallelDiffusion::transform(Options& state) {
     // Heat transfer
     Field3D E = + FV::Div_par_K_Grad_par(
       Dn * advection_factor * Pn, logPn);        // Pressure advection
-    if (thermal_conduction) {
+    if (perpendicular_conduction) {
       E += FV::Div_par_K_Grad_par(kappa_n, Tn);   // Conduction
     }
     add(species["energy_source"], E);
 
     Field3D F = 0.0;
-    if (IS_SET(species["velocity"]) and viscosity) {
+    if (IS_SET(species["velocity"]) and perpendicular_viscosity) {
       // Relationship between heat conduction and viscosity for neutral
       // gas Chapman, Cowling "The Mathematical Theory of Non-Uniform
       // Gases", CUP 1952 Ferziger, Kaper "Mathematical Theory of