noun

• (botany) A plant of the genus Iris, common in the northern hemisphere, and generally having attractive blooms (See Iris (plant) on Wikipedia.Wikipedia).
  "Breezes blowing from beds of iris quickened her breath with their perfume; she saw the tufted lilacs sway in the wind, and the streamers of mauve-tinted wistaria swinging, all a-glisten with golden bees; she saw a crimson cardinal winging through the foliage, and amorous tanagers flashing like scarlet flames athwart the pines."
• (anatomy) The contractile membrane perforated by the pupil, which adjusts to control the amount of light reaching the retina, and which forms the colored portion of the eye (See Iris (anatomy) on Wikipedia.Wikipedia).
• (photography, cinematography) A diaphragm used to regulate the size of a hole, especially as a way of controlling the amount of light reaching a lens.
• (poetic) A rainbow, or other colourful refraction of light.

verb

• (of an aperture, lens, or door) To open or close in the manner of an iris.
• (literary) To cause (something) to shine with the colours of the rainbow; to make iridescent.
  "Pure, transparent, glistening in the sun, and irised by a thousand hues, which float and wave and spread in graceful and ceaseless motion on its surface!"

name

• (Greek mythology) A messenger of the gods, and goddess of rainbows.
  "What's the matter, That this distemper'd messenger of wet, The many-colour'd Iris, rounds thine eye?"
• (astronomy) 7 Iris, a main belt asteroid.