An adjustable diaphragm by which the diameter of an approximately circular opening may be controlled, as for regulating the aperture of a lens; it consists of a number of movable thin curved plates fastened at regular intervals around the inside of a ring, the positions of which are simultaneously adjusted by a single knob on the outside of the lens. It is used in cameras and microscopes.

plural of iris diaphragm

A muscle of the eye, serving to dilate the iris.

plural of iris dilator muscle

plural of iris pigmented epithelium

The black colored layer of the iris, located behind the iris.

(sumo) a ring-entering ceremony performed by rikishi, in the juryo and higher divisions, upon entering the dohyo

ninjutsu techniques for stealth and infiltration

(sumo) A group ring-entering ceremony performed by all members of the makuuchi division, except the yokozuna, after the juryo bouts.