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]

The Collaborative International Dictionary of English v.0.48:

Pierce \Pierce\, v. t. [imp. & p. p. Pierced; p. pr. & vb. n.
   Piercing.] [OE. percen, F. percer, OF. percier, perchier,
   parchier; perh. fr. (assumed) LL. pertusiare for pertusare,
   fr. L. pertundere, pertusum, to beat, push, bore through; per
   through + tundere to beat: cf. OF. pertuisier to pierce, F.
   pertuis a hole. Cf. Contuse, Parch, Pertuse.]
   1. To thrust into, penetrate, or transfix, with a pointed
      instrument. "I pierce . . . her tender side." --Dryden.
      [1913 Webster]

   2. To penetrate; to enter; to force a way into or through; to
      pass into or through; as, to pierce the enemy's line; a
      shot pierced the ship.
      [1913 Webster]

   3. Fig.: To penetrate; to affect deeply; as, to pierce a
      mystery. "Pierced with grief." --Pope.
      [1913 Webster]

            Can no prayers pierce thee?           --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

piercing
    adj 1: having or demonstrating ability to recognize or draw fine
           distinctions; "an acute observer of politics and
           politicians"; "incisive comments"; "icy knifelike
           reasoning"; "as sharp and incisive as the stroke of a
           fang"; "penetrating insight"; "frequent penetrative
           observations" [syn: acute, discriminating,
           incisive, keen, knifelike, penetrating,
           penetrative, piercing, sharp]
    2: painful as if caused by a sharp instrument; "a cutting wind";
       "keen winds"; "knifelike cold"; "piercing knifelike pains";
       "piercing cold"; "piercing criticism"; "a stabbing pain";
       "lancinating pain" [syn: cutting, keen, knifelike,
       piercing, stabbing, lancinate, lancinating]

Moby Thesaurus II by Grady Ward, 1.0:

271 Moby Thesaurus words for "piercing":
   Siberian, absorbing, acerb, acerbate, acerbic, acid, acidic,
   acidulent, acidulous, acrid, acrimonious, acupunctuation,
   acupuncture, acute, afflictive, agonizing, algid, apperceptive,
   appercipient, arctic, argute, arresting, asperous, astringent,
   astute, atrocious, bayonetting, below zero, biting, bitter,
   bitterly cold, blaring, bleak, booming, bore, boreal, boring,
   brisk, broach, brumal, caustic, chilling, cogent, cold,
   cold as charity, cold as death, cold as ice, cold as marble,
   corroding, corrosive, cramping, creaky, crisp, cruel, cutting,
   deafening, deep, deep-felt, deepgoing, discerning, distressing,
   double-edged, drastic, drill hole, driving, ear-piercing,
   ear-rending, ear-splitting, earsplitting, earthshaking, edged,
   effective, empiercement, enthralling, entrancing, escharotic,
   excessive, excruciating, exorbitant, exquisite, extravagant,
   extreme, farseeing, farsighted, fascinating, fierce, fixing,
   forceful, forcible, foreseeing, foresighted, forethoughted,
   forethoughtful, forte, fortissimo, freezing, freezing cold, frigid,
   frosty, full, furious, gelid, glacial, gnawing, goring, grave,
   great, griping, gripping, gutsy, hard, harrowing, harsh, heartfelt,
   hibernal, hiemal, high, high-pitched, homefelt, howling, hurtful,
   hurting, hyperborean, ice-cold, ice-encrusted, icelike, icy,
   immoderate, impalement, imperative, impressive, incisive,
   inclement, indelible, intemperate, intense, irritating, keen,
   keening, knifelike, knifing, lancing, longheaded, longsighted,
   loud, loud-sounding, loudish, mordacious, mordant, nervous,
   nipping, nippy, nose-tickling, numbing, outrageous, painful,
   paroxysmal, pealing, penetrating, penetration, perceptive,
   percipient, perforation, perspicacious, perspicuous, pervading,
   pinching, piping, piquant, plangent, poignant, powerful, pricking,
   probing, profound, provident, punching, punchy, puncture,
   puncturing, pungent, racking, raw, reedy, reeking, resounding,
   rigorous, ringing, roaring, rough, sagacious, scathing, scorching,
   screaky, screaming, screeching, screechy, searching, sensational,
   severe, sharp, shooting, shrieking, shrieky, shrill, sinewed,
   sinewy, skewering, slashing, sleety, slushy, snappy, sonorous,
   sour, spasmatic, spasmic, spasmodic, spellbinding, splitting,
   squeaking, squeaky, stabbing, stentoraphonic, stentorian,
   stentorious, stinging, stone-cold, strident, striking, stringent,
   strong, subzero, supercooled, tart, telling, terebration,
   the sword, thin, thundering, thunderous, tonitruant, tonitruous,
   tormenting, torturous, tough, transfixation, transfixion,
   transforation, treble, trenchant, trepanning, trephining, ululant,
   unconscionable, understanding, vehement, venomous, vigorous,
   violent, virulent, vital, vitriolic, wailing, whining, whistling,
   window-rattling, winterbound, winterlike, wintery, wintry,
   withering