subsurface

From sub- +‎ surface.

subsurface (plural subsurfaces)

1. Something that is below the layer that is on the surface.

   Before we could lay the flooring we had to lay a subsurface under it to keep it flat and support it.

2. (countable, mathematics) A surface which is a submanifold of another surface.

subsurface (not comparable)

1. Below the surface.

   variations in subsurface conditions

From sub- +‎ surfaco +‎ -e.

• IPA^(key): /sub.sur.ˈfa.t͡se/

subsurface

1. subsurfacely, below the surface

• subsurfaca