īˈridēəm, ə̇ˈr- noun
( -s )
Usage: often attributive
Etymology: New Latin, from irid- + -ium; from the colorful appearance of some of its solutions
: a silver-white hard brittle very heavy chiefly trivalent and tetravalent metallic element of the platinum group that occurs usually as a native alloy with platinum or with osmium in iridosmine, is resistant to chemical attack at ordinary temperatures, and is used especially in hardening platinum for alloys suitable for surgical instruments, electrical and other scientific apparatus, jewelry, and the points of gold pens — symbol Ir ; see element table