subcellar
1 of 2adjective
sub·cel·lar ˈsəb-ˌse-lər 
variants or sub-cellar
: located below a cellar
the subcellar stairwell
subcellar
2 of 2noun
variants or sub-cellar
plural subcellars or sub-cellars
: a cellar that is below another cellar : subbasement
The owner … hired the architect … to design and build a four-story building, with a raised basement and a subcellar …
Albert Amateau
Albert Amateau… the institute's … vault, the subcellar archive with no windows … Donald Antrim
Donald Antrim
Word History
First Known Use
Adjective
1845, in the meaning defined above
Noun
1838, in the meaning defined above