General English

General Science

  • noun a small hole in a camera between the lens and the film, normally variable in size to adjust the amount of light passing through it to the film
  • noun the coloured part of the eye, which expands and contracts the pupil
  • noun a plant with coloured flowers and sword-shaped leaves.


  • An adjustable circular shutter of overlapping leaves used inspotlights to vary the diameter of the beam; it is also used in camerasand other optical instruments to vary the diameter of an aperture.