iris [LME] In classical mythology Iris was the goddess of the rainbow and a messenger of the gods. People saw the rainbow as a bridge or road let down from heaven for her to carry her messages along. The Latin and Greek word iris, taken from her name and meaning ‘rainbow’, is also in iridescent [L18th] and the name of the chemical element iridium [E19th], which forms compounds of various colours. The name iris [LME] for the membrane behind the cornea of the eye appears to derive from the variety of its colours. As a name for a flowering plant, iris dates from the late Middle Ages.