http://en.wikipedia.org/wiki/Iridescence

Etymology

The word iridescence is derived in part from the Latin word iris (pl. irides), meaning “rainbow“, which in turn derives from the goddess Iris of Greek mythology, who is the personification of the rainbow and acted as a messenger of the gods. Goniochromism is derived from the Greek words gonia, which means angle, and chroma, which means color.

i suffer from iritis