Lytta vesicatoria

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. [1913 Webster]

And painful blisters swelled my tender hands. --Grainger. [1913 Webster]

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. [1913 Webster]

3. A vesicatory; a plaster of Spanish flies, or other matter, applied to raise a blister. --Dunglison. [1913 Webster]

{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}. [1913 Webster]