Breadcrumb Home > Dictionary > Index I iris diaphragm: Meaning and Definition of Find definitions for: i'ris di"aphragm Pronunciation: [key] — Optics, Photog. Optics,Photog. a composite diaphragm with a central aperture readily adjustable for size, used to regulate the amount of light admitted to a lens or optical system. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. irisation iris diaphragm shutter TrendingHere are the facts and trivia that people are buzzing about. Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 12 Steps to a New Year New Year's Resolution to Slim Down? Martin Luther King Speeches Books of the Bible: Old Testament Books in Order ✖ Related Content Daily Word Quiz: picaresque Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language