isinglass Meaning, Definition & Usage

  1. noun any of various minerals consisting of hydrous silicates of aluminum or potassium etc. that crystallize in forms that allow perfect cleavage into very thin leaves; used as dielectrics because of their resistance to electricity
    mica.

WordNet

I"sin*glass noun
Etymology
Prob. corrupted fr. D. huizenblas (akin to G. hausenblase), lit., bladder of the huso, or large sturgeon; huizen sturgeon + blas bladder. Cf. Bladder, Blast a gust of wind.
Definitions
  1. A semitransparent, whitish, and very pure from of gelatin, chiefly prepared from the sounds or air bladders of various species of sturgeons (as the Acipenser huso) found in the of Western Russia. It used for making jellies, as a clarifier, etc. Cheaper forms of gelatin are not unfrequently so called. Called also fish glue.
  2. (Min.) A popular name for mica, especially when in thin sheets.

Webster 1913