the conventional term would be
–adjective
1.
displaying a play of lustrous colors like those of the rainbow.
–noun
2.
an iridescent cloth, material, or other substance: new fall dresses of imported iridescents.
In my opinion, which I'm applying to Linkin Park's Song Iridescent is as follows: A beautiful song that starts out with the
perspective of complete and utter sadness and devastation, which could be a possible reference to a death of a close friend (i.e killed right in front of you in during a war) or a torn family that resulted from a divorce. Along with that
introduction, the medium of the piano is used which helps
emphasize the emotions of isolation in the cold world. After the first verse and chorus, more and more ambient sounds are added in
contribution to a gradual climax of significance to their message. Let all of your sadness go, because it wasn't your fault that your friend was killed in combat or if you're parents left you. Instead of harboring the malady of sadness and frustration, forgive yourself and let go of the guilt you held on to.