Source : Webster's Revised Unabridged Dictionary (1913)

Irritant \Ir"ri*tant\, n. [Cf. F. irritant.]
   1. That which irritates or excites.

   2. (Physiol. & Med.) Any agent by which irritation is
      produced; as, a chemical irritant; a mechanical or
      electrical irritant.

   3. (Toxicology) A poison that produces inflammation.

   {Counter irritant}. See under {Counter}.

   {Pure irritant} (Toxicology), a poison that produces
      inflammation without any corrosive action upon the
      tissues.

Counter \Coun"ter\, a.
   Contrary; opposite; contrasted; opposed; adverse;
   antagonistic; as, a counter current; a counter revolution; a
   counter poison; a counter agent; counter fugue. ``Innumerable
   facts attesting the counter principle.'' --I. Taylor.

   {Counter approach} (Fort.), a trench or work pushed forward
      from defensive works to meet the approaches of besiegers.
      See {Approach}.

   {Counter bond} (Law), in old practice, a bond to secure one
      who has given bond for another.

   {Counter brace}. See {Counter brace}, in Vocabulary.

   {Counter deed} (Law), a secret writing which destroys,
      invalidates, or alters, a public deed.

   {Counter distinction}, contradistinction. [Obs.]

   {Counter drain}, a drain at the foot of the embankment of a
      canal or watercourse, for carrying off the water that may
      soak through.

   {Counter extension} (Surg.), the fixation of the upper part
      of a limb, while extension is practiced on the lower part,
      as in cases of luxation or fracture.

   {Counter fissure} (Surg.) Same as {Contrafissure}.

   {Counter indication}. (Med.) Same as {Contraindication}.

   {Counter irritant} (Med.), an irritant to produce a blister,
      a pustular eruption, or other irritation in some part of
      the body, in order to relieve an existing irritation in
      some other part. ``Counter irritants are of as great use
      in moral as in physical diseases.'' --Macaulay.

   {Counter irritation} (Med.), the act or the result of
      applying a counter irritant.

   {Counter opening}, an aperture or vent on the opposite side,
      or in a different place. 

   {Counter parole} (Mil.), a word in addition to the password,
      given in time of alarm as a signal.

   {Counter plea} (Law), a replication to a plea. --Cowell.

   {Counter pressure}, force or pressure that acts in a contrary
      direction to some other opposing pressure.

   {Counter project}, a project, scheme, or proposal brought
      forward in opposition to another, as in the negotiation of
      a treaty. --Swift.

   {Counter proof}, in engraving, a print taken off from another
      just printed, which, by being passed through the press,
      gives a copy in reverse, and of course in the same
      position as that of plate from which the first was
      printed, the object being to enable the engraver to
      inspect the state of the plate.

   {Counter revolution}, a revolution opposed to a former one,
      and restoring a former state of things.

   {Counter revolutionist}, one engaged in, or befriending, a
      counter revolution.

   {Counter round} (Mil.), a body of officers whose duty it is
      to visit and inspect the rounds and sentinels.

   {Counter sea} (Naut.), a sea running in an opposite direction
      from the wind.

   {Counter sense}, opposite meaning.

   {Counter signal}, a signal to answer or correspond to
      another.

   {Counter signature}, the name of a secretary or other officer
      countersigned to a writing. --Tooke.

   {Counter slope}, an overhanging slope; as, a wall with a
      counter slope. --Mahan.

   {Counter statement}, a statement made in opposition to, or
      denial of, another statement.

   {Counter surety}, a counter bond, or a surety to secure one
      who has given security.

   {Counter tally}, a tally corresponding to another.

   {Counter tide}, contrary tide.