Read the dictionary definition of iris. All definitions for this word.
1. diaphragm consisting of thin overlapping plates that can be adjusted to change the diameter of a central opening
2. muscular diaphragm that controls the size of the pupil which in turn controls the amount of light that enters the eye; it forms the colored portion of the eye
3. plants with sword-shaped leaves and erect stalks bearing bright-colored flowers composed of three petals and three drooping sepals