The Collaborative International Dictionary of English v.0.48:
Glacial \Gla"cial\, a. [L. glacialis, from glacies ice: cf. F.
1. Pertaining to ice or to its action; consisting of ice;
frozen; icy; esp., pertaining to glaciers; as, glacial
2. (Chem.) Resembling ice; having the appearance and
consistency of ice; -- said of certain solid compounds;
as, glacial phosphoric or acetic acids.
Glacial acid (Chem.), an acid of such strength or purity as
to crystallize at an ordinary temperature, in an icelike
form; as acetic or carbolic acid.
Glacial drift (Geol.), earth and rocks which have been
transported by moving ice, land ice, or icebergs; bowlder
Glacial epoch or Glacial period (Geol.), a period during
which the climate of the modern temperate regions was
polar, and ice covered large portions of the northern
hemisphere to the mountain tops.
Glacial theory or Glacial hypothesis. (Geol.) See
Glacier theory, under Glacier.