"turf, slice of earth with grass on it," mid-15c., apparently from Middle Dutch sode "turf," or Middle Low German sode, both related to Old Frisian satha "sod," all of uncertain origin. Perhaps the notion is water saturation and the group is related to sog. The (old) sod "Ireland" is from 1812.
c.1400, "to cover with sod," from sod (n.). Related: Sodded; sodding.
in sod off (1960), British slang term of dismissal; see sod (n.2).