The Collaborative International Dictionary of English v.0.48:

Piercing \Pier"cing\, a.
   Forcibly entering, or adapted to enter, at or by a point;
   perforating; penetrating; keen; -- used also figuratively;
   as, a piercing instrument, or thrust. "Piercing eloquence."
   --Shak.
   [1913 Webster] -- Pier"cing*ly, adv. -- Pier"cing*ness,
   n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

piercingly
    adv 1: extremely and sharply; "it was bitterly cold"; "bitter
           cold" [syn: piercingly, bitterly, bitingly,
           bitter]
    2: in a shrill voice; "she sang rather shrilly" [syn: shrilly,
       piercingly]