earthhouse
An underground chamber or habitation; a souterrain.
archaic
heirlooms heaped inside the earth-house, because long ago, with deliberate care, some forgotten person had deposited the whole rich inheritance of a high-born race in this ancient cache.
There were many otherA dwelling that has been built to blend in with the surrounding landscape, being mostly underground with soil piled against its walls or with a grassy contoured roof; it may also be completely underground, or have a topping of intensive growth.
Where it comes from
Inherited from Middle English erthe hous, from Old English eorþhūs, from Proto-West Germanic *erþahūs, from Proto-Germanic *erþahūsą, equivalent to earth + house.
Adapted from the Wiktionary entry earthhouse (CC BY-SA 4.0).