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iris

n. a muscular disk that surrounds the pupil of the eye and controls the amount of light entering the eye by contraction or relaxation. The stroma of the iris, which faces the cornea, contains a pigment that gives the eye its coloration; the back of the iris is lined with a dark pigment that restricts light entry to the pupil, regardless of the apparent color of the iris.

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Psychology term of the day

November 21st 2024