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.
And painful blisters swelled my tender hands.
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.
3. A vesicatory; a plaster of Spanish flies, or other matter,
applied to raise a blister. --Dunglison.
Blister beetle, a beetle used to raise blisters, esp. the
Lytta vesicatoria (or Cantharis vesicatoria), called
Cantharis or Spanish fly by druggists. See
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.