The Collaborative International Dictionary of English v.0.48:

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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