noun. ['ˌɪˈrɪdiːəm'] a heavy brittle metallic element of the platinum group; used in alloys; occurs in natural alloys with platinum or osmium.
1. Noun, singular or mass Spark plugs made with iridium electrodes have a tolerance to heat above that of platinum types. 2. Adjective Many fakes have the words "iridium tip" and "made in Germany" stamped on them.
