It's the Eskimo term for any dwelling, not just those made of ice
[DOC] [TLE] Igloo - New World Encyclopedia [PAR] As such, the Inuit do not restrict the use of this term exclusively to snow ... A highly 
functional shelter, the igloo is also aesthetically pleasing; its shape ... Hunters 
while out on the land or sea ice may camp in one of these iglooit for one or two 
nights.