/i rid"ee euhm, uy rid"-/ , n. Chem.
a precious metallic element resembling platinum: used in platinum alloys and for the points of gold pens. Symbol: Ir; at. wt.: 192.2; at. no.: 77; sp. gr.: 22.4 at 20°C.
[ 1804; irid-, s. of iris rainbow (see IRIS) + -IUM; so named from its iridescence when dissolved in hydrochloric acid ]