Ground ice
A general term referring to all types of ice contained in freezing and seasonally frozen ground and permafrost (Van Everdingen, 1998).
Definition courtesy of IPCC AR4.
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.