noun Chiefly Archaeology.
Examples from the Web for souterrain
It is a small fort, and on the top we saw the narrow entrance to the souterrain.
She describes it as "a souterrain containing six chambers, with a length of eighty-seven feet exclusive of a flooded chamber."
On the other hand, there appears to be no objection to growing crops on the top of a souterrain.
In many cases we do find the entrance to a souterrain is in a fort.
My best thanks are also due to Mrs. Hobson for allowing me to make use of her photograph of the entrance to this souterrain.