Definify.com

Webster 1913 Edition

Understratum

Un′der-straˊtum

,

Noun.

;

pl. L.

Understrata

, E.

Understratums

.

The layer, or stratum, of earth on which the mold, or soil, rests; subsoil.

Webster 1828 Edition

Understratum

UNDERSTRA'TUM

,

Noun.

Subsoil; the bed or layer of earth on which the old or soil rests.