Source : Webster's Revised Unabridged Dictionary (1913)

High \High\, adv.
   In a high manner; in a high place; to a great altitude; to a
   great degree; largely; in a superior manner; eminently;
   powerfully. ``And reasoned high.`` --Milton. ``I can not
   reach so high.'' --Shak.

   Note: High is extensively used in the formation of compound
         words, most of which are of very obvious signification;
         as, high-aimed, high-arched, high-aspiring,
         high-bearing, high-boasting, high-browed, high-crested,
         high-crowned, high-designing, high-engendered,
         high-feeding, high-flaming, high-flavored, high-gazing,
         high-heaped, high-heeled, high-priced, high-reared,
         high-resolved, high-rigged, high-seated,
         high-shouldered, high-soaring, high-towering,
         high-voiced, and the like.

   {High and low}, everywhere; in all supposable places; as, I
      hunted high and low. [Colloq.]

Source : WordNet®

high and low
     adv : everywhere; "searched high and low"