Definition of indusium in US English:


nounPlural indusia

  • A thin membranous covering, especially a shield covering a sorus on a fern frond.

    • ‘The leaf margins themselves are often reflexed to form false indusia that protect the sori.’
    • ‘The upper surface of the intermediate portion of the corpus callosum is covered by a thin veil of gray substance - the indusium griseum.’
    • ‘The latter is covered by the indusium griseum, a thin sheet of rudimentary cortex containing (on each side) the delicate medial and lateral longitudinal striae.’


Early 18th century: from Latin, literally ‘tunic’, from induere ‘put on, don’.