[1] : The Collaborative International Dictionary of English v.0.48

caustic \caus"tic\, caustical \caus"tical\, a. l. caustucs,
   ge. ?, fr. ? to burn. cf. calm, ink.
   1. capable of destroying the texture of anything or eating
      away its substance by chemical action; burning; corrosive;
      searing.
      1913 webster

   2. severe; satirical; sharp; as, a caustic remark.
      1913 webster

   caustic curve optics, a curve to which the ray of light,
      reflected or refracted by another curve, are tangents, the
      reflecting or refracting curve and the luminous point
      being in one plane.

   caustic lime. see under lime.

   caustic potash, caustic soda chem., the solid
      hydroxides potash, koh, and soda, naoh, or solutions
      of the same.

   caustic silver, nitrate of silver, lunar caustic.

   caustic surface optics, a surface to which rays reflected
      or refracted by another surface are tangents. caustic
      curves and surfaces are called catacaustic when formed by
      reflection, and diacaustic when formed by refraction.

   syn: stinging; cutting; pungent; searching.
        1913 webster
see also:
calm ink caustic curve caustic lime lime caustic potash 
caustic soda koh naoh caustic silver caustic surface 

[2] : The Collaborative International Dictionary of English v.0.48

caustic \cau"stic\, n. l. causticum sc. medicamentum. see
   caustic, a.
   1. any substance or means which, applied to animal or other
      organic tissue, burns, corrodes, or destroys it by
      chemical action; an escharotic.
      1913 webster

   2. optics a caustic curve or caustic surface.
      1913 webster
see also:
caustic 

[3] : WordNet (r) 2.0

caustic
     adj 1: harsh or corrosive in tone; "an acerbic tone piercing
            otherwise flowery prose"; "a barrage of acid
            comments"; "her acrid remarks make her many enemies";
            "bitter words"; "blistering criticism"; "caustic jokes
            about political assassination, talk-show hosts and
            medical ethics"; "a sulfurous denunciation" syn: acerb,
             acerbic, acid, acrid, bitter, blistering, sulfurous,
             sulphurous, venomous, virulent, vitriolic
     2: of a substance, especially a strong acid; capable of
        destroying or eating away by chemical action syn: corrosive,
         erosive, vitriolic
     n : any chemical substance that burns or destroys living tissue
see also:
acerb acerbic acid acrid bitter blistering 
sulfurous sulphurous venomous virulent vitriolic 
corrosive erosive 

[4] : Moby Thesaurus II by Grady Ward, 1.0

136 moby thesaurus words for "caustic":
   rabelaisian, acerb, acerbate, acerbic, acid, acidic, acidulent,
   acidulous, acrid, acrimonious, actual cautery, acute, amaroidal,
   angry, antagonistic, antipathetic, arc, asperous, astringent,
   belligerent, biting, bitter, bitter as gall, bow, brand,
   brand iron, branding iron, brisk, burning, catacaustic, catenary,
   cauter, cauterant, cauterizer, cautery, choleric, circle, clashing,
   coarse, colliding, conchoid, conflicting, corroding, corrosive,
   crisp, critical, crook, curl, curve, cutting, cynical, despiteful,
   destructive, diacaustic, discontented, double-edged, dry, edged,
   electrocautery, ellipse, embittered, escharotic, feeling evil,
   festoon, fierce, full of hate, hard, harsh, hateful, hook, hostile,
   hot iron, hyperbola, incisive, ironic, irritating, keen, lituus,
   lunar caustic, malevolent, malicious, malignant, mordacious,
   mordant, moxa, nose-tickling, out of humor, out of sorts,
   out of temper, parabola, penetrating, piercing, piquant, pithy,
   poignant, potential cautery, pungent, quarrelsome, radium,
   rancorous, rankled, repugnant, resentful, resenting, rigorous,
   rough, salty, sarcastic, sardonic, satiric, scathing, scorching,
   set against, severe, sharp, sinus, sore, sour, spiteful, splenetic,
   stabbing, stewing, stinging, strident, stringent, succinct, tart,
   terse, tracery, trenchant, vehement, venomous, violent, virulent,
   vitriolic, withering

Caustic >> C Words
Caustic, definition of term: Caustic
caustic_pag1.html

Caustic Soda >> C Words
Caustic Soda, definition of term: Caustic Soda
caustic+soda_pag1.html

Caustic Potash >> C Words
Caustic Potash, definition of term: Caustic Potash
caustic+potash_pag1.html

Lunar Caustic >> L Words
Lunar Caustic, definition of term: Lunar Caustic
lunar+caustic_pag1.html