The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

   2. (Chem.) Resembling ice; having the appearance and
      consistency of ice; -- said of certain solid compounds;
      as, glacial phosphoric or acetic acids.
      [1913 Webster]

   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 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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

glacial
    adj 1: relating to or derived from a glacier; "glacial deposit"
    2: devoid of warmth and cordiality; expressive of unfriendliness
       or disdain; "a frigid greeting"; "got a frosty reception"; "a
       frozen look on their faces"; "a glacial handshake"; "icy
       stare"; "wintry smile" [syn: frigid, frosty, frozen,
       glacial, icy, wintry]
    3: extremely cold; "an arctic climate"; "a frigid day"; "gelid
       waters of the North Atlantic"; "glacial winds"; "icy hands";
       "polar weather" [syn: arctic, frigid, gelid, glacial,
       icy, polar]

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "glacial":
   Siberian, algid, aloof, arctic, below zero, biting, bitter,
   bitterly cold, blast-frozen, bleak, boreal, brisk, brumal, chill,
   chilly, cold, cold as charity, cold as death, cold as ice,
   cold as marble, congealed, cool, crisp, cutting, distant,
   emotionless, exclusive, freezing, freezing cold, frigid,
   frostbitten, frostnipped, frosty, frozen, frozen solid, gelid,
   hibernal, hiemal, hyperborean, ice, ice-cold, ice-encrusted,
   icelike, icy, icy-cold, inaccessible, inclement, indifferent, keen,
   nipping, nippy, numbing, penetrating, piercing, pinching,
   quick-frozen, raw, remote, reserved, rigorous, seclusive, severe,
   sharp, sharp-frozen, sleety, slushy, snappy, standoffish,
   stone-cold, subzero, supercooled, unapproachable, unemotional,
   winterbound, winterlike, wintery, wintry, withdrawn