Iridocinetic is a medical term that refers to the movement of the iris in response to light. The spelling of iridocinetic can be broken down using the International Phonetic Alphabet (IPA) as [ˌɪrɪdoʊsaɪˈnɛtɪk]. The prefix "irido-" is derived from the Greek word for iris, while "cinetic" comes from the Greek word for motion, "kinetic". The final "t" in "kinetic" becomes a "c" when combined with the prefix, resulting in "cinetic". Thus, iridocinetic describes the movement of the iris in response to light.
Relating to the movements of the iris.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.