What does "glacial" mean?

Glacial: (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.