isinglass
UK[ˈaɪzɪŋɡlɑːs]US[ˈaɪzɪŋɡlæs]
n
A transparent, almost pure gelatin obtained from the air bladders of fish (especially sturgeon), used in making jellies, glue, and for clarifying beer and wine.
n
(dated) Mica in thin, transparent sheets.
Etymology
The word 'isinglass' has a deceptive English-sounding structure but originates from the obsolete Dutch term huizenblas, meaning "sturgeon's bladder." This term entered English in the 16th century as isen glass or ising glass. Over time, English speakers, unfamiliar with the Dutch components, reinterpreted the word by associating it with familiar elements: the first part was linked to 'ice' or the German Eisen (iron), and the second part was clearly identified as 'glass,' due to the material's transparent, sheet-like quality. This process of folk etymology completely obscured the original Dutch meaning, creating a new, logically coherent but historically inaccurate compound in the minds of English speakers. The later, geological meaning of "mica" arose from the visual similarity between thin sheets of mica and the prepared fish gelatin.
Analysis
This word is a loanword and a classic example of folk etymology. Its current spelling and pronunciation are the result of a long process of phonetic adaptation and reinterpretation of a foreign term within English.
Examples
Traditional recipes for certain jellies and desserts sometimes call for isinglass as a setting agent.
The brewer used isinglass to clarify the cask ale, ensuring it was bright and free from haze.
In the 19th century, small panes of isinglass were used as windows in stoves and carriages.