Understratum

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Understratum \Un"der*stra`tum\, n.; pl. L. {Understrata}, E.
     {Understratums}.
     The layer, or stratum, of earth on which the mold, or soil,
     rests; subsoil.
     [1913 Webster]