Source : Webster's Revised Unabridged Dictionary (1913)

Glacial \Gla"cial\, a. [L. glacialis, from glacies ice: cf. F.
   glacial.]
   1. Pertaining to ice or to its action; consisting of ice;
      frozen; icy; esp., pertaining to glaciers; as, glacial
      phenomena. --Lyell.

   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
      drift.

   {Glacial} {epoch or 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 hypothesis}. (Geol.) See {Glacier
      theory}, under {Glacier}.