iris

(noun) plants with sword-shaped leaves and erect stalks bearing bright-colored flowers composed of three petals and three drooping sepals. Synonyms: flag, fleur-de-lis, sword lily.

(noun) 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.

(noun) diaphragm consisting of thin overlapping plates that can be adjusted to change the diameter of a central opening. Synonyms: iris diaphragm.