Blister fly

Blister \Blis"ter\, n. [OE.; akin to OD. bluyster, fr. the same
   root as blast, bladder, blow. See {Blow} to eject wind.]
   1. A vesicle of the skin, containing watery matter or serum,
      whether occasioned by a burn or other injury, or by a
      vesicatory; a collection of serous fluid causing a
      bladderlike elevation of the cuticle.
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            And painful blisters swelled my tender hands.
                                                  --Grainger.
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   2. Any elevation made by the separation of the film or skin,
      as on plants; or by the swelling of the substance at the
      surface, as on steel.
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   3. A vesicatory; a plaster of Spanish flies, or other matter,
      applied to raise a blister. --Dunglison.
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   {Blister beetle}, a beetle used to raise blisters, esp. the
      {Lytta vesicatoria} (or {Cantharis vesicatoria}), called
      {Cantharis} or {Spanish fly} by druggists. See
      {Cantharis}.

   {Blister fly}, a blister beetle.

   {Blister plaster}, a plaster designed to raise a blister; --
      usually made of Spanish flies.

   {Blister steel}, crude steel formed from wrought iron by
      cementation; -- so called because of its blistered
      surface. Called also {blistered steel}.

   {Blood blister}. See under {Blood}.
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