If something is iridescent, it shows those sliding rainbow colours — the ones that look different when you tilt the thing or when the light changes. An iridescent bubble, iridescent insect wings, an iridescent dress under stage lights. It is the adjective that matches the noun iridescence. People use it in science, in fashion, and when they want to describe a surface carefully. Though actually, it is not the same as painting rainbow stripes, and it is not the same as fluorescent, which is about glowing. Iridescent means the colours seem to live in the shine and shift as you look.

虹彩的、會隨光線變出彩虹色的