WordWeb Online

1. Varying in colour when seen in different lights or from different angles
   "iridescent silk"; "a dragonfly hovered, vibrating and iridescent";
   - changeable, chatoyant, shot
    
2. Having a play of lustrous rainbow colours
   "an iridescent oil slick"; "iridescent clouds looking like mother-of-pearl";
   - nacreous, opalescent, opaline, pearlescent

See also: bright, colorful [US], colourful [Brit, Cdn]

Encyclopedia: Iridescent