nounpl. -·lums or -·la
the altered soil or material overlying the parent material, often including the A-horizon and the B-horizon
Origin of solumModern Latin from L, base, soil
nounpl. so·la, or so·lums
The upper layers of a soil profile in which topsoil formation occurs.
Origin of solumLatin base, ground
From Latin solum (“base, bottom; soil").