(adj) having a play of lustrous rainbow colors, Syn. nacreous, pearlescent, opaline, opalescent, Example:an iridescent oil slick; nacreous (or pearlescent) clouds looking like mother-of-pearl; a milky opalescent (or opaline) luster
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
a. [ L. iris, iridis, the rainbow: cf. F. iridescent. ] Having colors like the rainbow; exhibiting a play of changeable colors; nacreous; prismatic; as, iridescent glass. See iridescence. [ 1913 Webster ]