1. a transparent or translucent substance obtained from the swim bladder of fish, used as a clarifying agent in beverages and as a glue or sizing material
Usage: also called fish glue; commonly used in winemaking and beer production
2. a thin, transparent sheet of mica or a similar material, historically used as a window pane or in lanterns
Usage: archaic; also called muscovy glass

Examples

• Winemakers use isinglass to clarify wine by removing suspended particles.
• The brewery added isinglass to the beer to improve its clarity.
• Medieval lanterns were sometimes fitted with sheets of isinglass instead of glass.
• Isinglass is derived from the swim bladders of sturgeon and other large fish.
• The transparent isinglass pane allowed light to enter the old lantern.
• Many craft breweries still rely on isinglass as a natural fining agent.