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], iridesce, iridescence

Encyclopedia: Iridescent