DCHP-1 Online
key-block Arctic 
n. a polygonal block of snow dropped into place in the centre of an igloo dome and serving to lock the structure firmly together. See picture at igloo.
See also: igloo keystone (block)
- 1823 The huts themselves, are entirely made of square blocks of solid snow, with a larger key-block at the top of the rotunda.
- 1957 The walls usually fell in just as I was about to fit the key-block in the top.
- 1823 The huts themselves, are entirely made of square blocks of solid snow, with a larger key-block at the top of the rotunda.