Definition of fibroin in US English:



  • A protein that is the chief constituent of silk and spider webs.

    • ‘The mechanisms are not well defined, but iron and tin will promote the photo-oxidation of the silk fibroin.’
    • ‘Molecular elasticity is associated with a select number of polypeptides and proteins, such as titin, Lustrin A, silk fibroin, and spider silk dragline protein.’
    • ‘A molecule of capture fibroin is made of the same two components but in very different proportions: it consists almost entirely of tangles, with very few microcrystals.’
    • ‘The raw silk fiber actually consists of two filaments called fibroin bound by a soluble silk gum called sericin.’
    • ‘As water volume decreased and the concentration of fibroin increased, the proteins folded in on themselves, forming round structures called micelles.’


Mid 19th century: from fibro- + -in.