Main definitions of iris in US English:

: iris1Iris2



  • 1A flat, colored, ring-shaped membrane behind the cornea of the eye, with an adjustable circular opening (pupil) in the center.

    • ‘The crystalline lens is a transparent structure situated behind the iris.’
    • ‘The thin sheet of circular muscle of the iris which constricts the pupil of the eye is also known as a sphincter.’
    • ‘When the trabecular meshwork is blocked at the junction of the cornea and iris, the resulting rise in intraocular pressure can reach dangerously high levels and damage the optic nerve.’
    • ‘We know that when eyes are shut, oxygen can reach the cornea from the iris solely by way of the stagnant aqueous humor.’
    • ‘Adhesions may also develop between the iris and cornea (peripheral anterior synechiae), covering up the trabecular drainage meshwork.’
    • ‘The cornea, the pupillary opening within the iris, the lens, and the aqueous and vitreous humor combine to form the refractive media of the eye.’
    • ‘The aqueous humour that fills the anterior chamber (front part of the eye) is produced by the ciliary body, just behind the iris.’
    • ‘The colored circular membrane in the eye just behind the cornea is called the iris.’
    • ‘External examination includes a penlight evaluation of the lids, conjunctiva, sclera, cornea, and iris.’
    • ‘The liquid hydrogel, based on a dendritic macromer, has optical properties similar to the cornea, the layer that covers the iris and pupil of the eye.’
    • ‘The fluid made by the ciliary body (a thickening of the blood vessel tunic) inside the eye nourishes the lens and, cornea and the colored iris.’
    • ‘Nourishment for your cornea comes from your tears and the aqueous humor - the clear fluid that fills the space between your iris and cornea.’
    • ‘His dissection of the eye yielded the distinction between cornea, retina, iris, and chorioid coat.’
    • ‘Uveitis, or inflammation of the iris, ciliary body or choroid, may also cause light sensitivity, pain and loss of vision.’
    • ‘The walking wounded were often blind, their pupils, irises, and corneas burned out.’
    • ‘The middle layer is a vascular, pigmented layer consisting of the iris, ciliary body, and choroid.’
    • ‘It's considered superior to a circular iris in that the pupil can open wider in darkness.’
    • ‘Anterior uveitis, which is diagnosed by slit lamp examination, refers to inflammation of the iris and ciliary body and occurs frequently with herpes zoster ophthalmicus.’
    • ‘The cornea is the clear part of the outer layer of the eye that covers the iris and the pupil.’
    • ‘The iridocorneal angle usually is a wide angle, is formed by the iris and the cornea, and encircles the anterior chamber.’
    1. 1.1 An adjustable diaphragm of thin overlapping plates for regulating the size of a central hole, especially for the admission of light to a lens.
      • ‘He was in the habit of using his microscope iris to adjust the valve settings on the engine of his lovingly maintained Triumph Dolomite Sprint.’
      • ‘The incorporation of a variable iris diaphragm into the optical couplers allows the power of the beams to be independently set.’
      • ‘These iris diaphragms are made from tempered and blackened steel leaves mounted in a metal ring.’
      • ‘These smooth action iris diaphragms are all fabricated in black anodized corrosion resistant frames containing spring-steel leaves.’
      • ‘In experiments to find the effect of lens diameter he invented the familiar iris diaphragm.’
      • ‘These iris diaphragm valves work similar to the iris of a camera.’
      • ‘The caged-probes were subsequently photoreleased in discrete regions of the cell with a 5 second UV pulse focused through an iris diaphragm.’
      • ‘The iris leaves of Melles Griot iris diaphragms, constructed of corrosion-resistant, blackened spring-steel, are mounted on a low-friction bearing pins.’
      • ‘The field iris diaphragm controls the area of the circle of light illumination the specimen.’
      • ‘Some of our iris diaphragms use a two-iris system to allow them to be closed completely to a zero aperture.’
      • ‘Many stereomicroscopes having the parallel or common main objective design are coupled to illumination stands that are equipped with iris diaphragms.’
      • ‘It has an iris diaphragm, and an optical and LCD screen viewfinder.’
      • ‘For photobleaching experiments, the iris of the microscope was reduced to the minimum diameter so that only a small region of the sample was excited.’
      • ‘Consisting of a grid of iris diaphragms, the facade's surface has changing apertures.’
      • ‘This can be very problematic with small deeply housed iris diaphragms as the process tends to loosen the rest of the leaves.’
      • ‘Focusing the condenser on a microscope without an iris diaphragm is carried out by removing the slide from the stage and placing a piece of thin card half-way across the light source aperture.’
      • ‘Use the lever adjustment to close the field iris diaphragm until you begin to see the leaves in the viewfield.’
      • ‘Implicit in such microscopes are design elements such as solid metal alloys, high quality prisms rather than mirrors and iris diaphragms not disk type diaphragms, among others.’
      • ‘This is the job of the iris diaphragm, a series of overlapping metal plates that can fold in on each other or expand out.’
      • ‘It has an adjustable iris diaphragm, with up to 10 mm clear aperture, mounted in a 30 mm diameter barrel.’
  • 2A plant with sword-shaped leaves and showy flowers, typically purple, yellow, or white. Native to both Eurasia and North America, it is widely cultivated as an ornamental.

    Genus Iris, family Iridaceae (the iris family): many species and numerous hybrids, including the crested dwarf iris (I. cristata) and the sweet iris (I. pallida). The iris family also includes the gladioli, crocuses, and freesias

    • ‘Calla lilies, iris, geraniums and hibiscus bloomed here as well as a variety of other plants.’
    • ‘I have also seen little leaves forming on my hardy water lilies and water irises rising up above the water reaching for the sun.’
    • ‘Michelle had painted a flower arrangement that overflowed with yellow lilies and blue irises with a fiery sunset-red background.’
    • ‘Plants like peonies, poppies, and irises should also be planted in the fall season.’
    • ‘Spring-flowering bulbs such as tulips, crocuses, hyacinths, daffodils, and irises are universal symbols of spring.’
    • ‘The garden includes ferns, hydrangeas, irises, waterlilies, camellias, rhododendrons, Japanese maples and fuchsias.’
    • ‘In and alongside the stream, a different suite of plants can be found including yellow iris, hemlock water-dropwort, lesser spearwort and brooklime.’
    • ‘It spreads by underground fleshy stems called rhizomes; rhizomes are found on many plants, from irises to agapanthus, from ferns to Bermuda grass.’
    • ‘Peonies, irises, daylilies, and delphiniums peak as phlox come into bud and astilbes begin to light up shady garden spots.’
    • ‘Plant reblooming irises in summer so they can root before winter.’
    • ‘It contains many pine trees, flower gardens, irises and ajisai in summer.’
    • ‘In summer, traditional perennials take over, and peonies, irises and hemerocallis fill the flowery brook.’
    • ‘You can also achieve this effect by planting moisture lovers, such as cardinal flower and Japanese iris, in a bucket or a washtub or by using heavy polyethylene plastic instead of a pond liner.’
    • ‘In the perennial gardens, the use of colorful and fragrant plants, including gladiolus, iris, tuberose and alstroemeria, is abundant.’
    • ‘Lined with turquoise tiles, the pool is surrounded by three small rectangular pools planted with irises and water lilies.’
    • ‘The newspaperman had a love for a myriad of different flower species and soon divided his interests between roses, irises, lilacs and native California plants.’
    • ‘Daffodils, iris, tulips, gladiolus, hyacinth, and daylilies are just some of the many bulb favorites.’
    • ‘Do not plant irises in crowded or completely shaded areas.’
    • ‘Some plants like ornamental grasses or irises may require knives, machetes, or even hatchets to get the job done, but it is worth it.’
    • ‘We landscaped last spring with Asian Jasmine edging, magnolias, azaleas, irises and spiral junipers next to the pool.’


  • no object, with adverbial of direction (of an aperture, typically that of a lens) open or close in the manner of an iris or iris diaphragm.

    • ‘Ann tugged at his arm and pointed down to the hull's underbelly: a round opening had irised out in it, brightly lit from inside.’
    • ‘As the last scene irised out to the familiar credits I was actually happy to have it all over.’
    • ‘A swirling vortex of yellow and white light irised open from a small dot to a man-sized portal just above the deck in front of Illeen.’


Modern Latin, via Latin from Greek iris ‘rainbow, iris’.




Main definitions of iris in US English:

: iris1Iris2


proper noun

Greek Mythology
  • The goddess of the rainbow, who acted as a messenger of the gods.