The Collaborative International Dictionary of English v.0.48:

Bleb \Bleb\, n. [Prov. E. bleb, bleib, blob, bubble, blister.
   This word belongs to the root of blub, blubber, blabber, and
   perh. blow to puff.]
   A large vesicle or bulla, usually containing a serous fluid;
   a blister; a bubble, as in water, glass, etc.
   [1913 Webster]

         Arsenic abounds with air blebs.          --Kirwan.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bleb
    n 1: (pathology) an elevation of the skin filled with serous
         fluid [syn: blister, bulla, bleb]