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: Most commonly used in winemaking and beer production; Also called fish glue or fish gelatin
2. A thin, transparent sheet of mica or a similar mineral substance, historically used as a window pane or in lanterns.
Usage: archaic or historical usage; largely replaced by glass in modern times

Examples

• Winemakers use isinglass to clarify wine by removing suspended particles.
• The brewery added isinglass to the beer to improve its clarity.
• In medieval times, isinglass was used as a substitute for glass in windows.
• Isinglass is a popular fining agent in the production of craft beers.
• The transparent isinglass sheets allowed light to pass through the old lantern.
• Vegetarians and vegans often avoid wines clarified with isinglass because it is animal-derived.