iris

noun

• 1a flat, colored, ring-shaped membrane behind the cornea of the eye, with an adjustable circular opening (pupil) in the center.
• (also iris diaphragm) an adjustable diaphragm of thin overlapping plates for regulating the size of a central hole, especially for the admission of light to a lens.

• 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

• 3a rainbow or a rainbowlike appearance.

verb

• (of an aperture, typically that of a lens) open or close in the manner of an iris or iris diaphragm.