Iridescence is the soft rainbow shine you see when colours seem to slide and change as the light moves, or as you move your eyes. A soap bubble has it. Oil on a wet road has it. Some beetle shells and peacock feathers have it too. The colours are not painted on as one fixed colour; they appear because the surface plays with light. The word is a noun: you talk about the iridescence of something. It is a fairly fancy word — science and careful description like it — but the thing itself is ordinary. Children see it every time they blow bubbles.

虹彩、彩虹般的光澤