Source : Webster's Revised Unabridged Dictionary (1913)

Iridescent \Ir`i*des"cent\ (?; 277), 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.

Source : WordNet®

iridescent
     adj 1: varying in color when seen in different lights or from
            different angles; "changeable taffeta"; "chatoyant (or
            shot) silk"; "a dragonfly hovered, vibrating and
            iridescent" [syn: {changeable}, {chatoyant}, {shot}]
     2: having a play of lustrous rainbow-like colors; "an
        iridescent oil slick"; "nacreous (or pearlescent) clouds
        looking like mother-of-pearl"; "a milky opalescent (or
        opaline) luster" [syn: {nacreous}, {opalescent}, {opaline},
         {pearlescent}]