glacial

Short definition from Wiktionary

Adjective

1. 1
   Of, or relating to glaciers.
2. 2
   Very slow.
3. 3
   Cold and icy.
4. 4
   Having the appearance of ice.
5. 5
   Cool and unfriendly.

Noun

1. 1
   A glacial period (colloquially known as an ice age).

Proper noun

1. 1
   Of the Pleistocene period dominated by the presence of glaciers.