Iridescent came to be in 1796, when some enthusiastic word maker took the Latin word iris (iridis), which means "rainbow," and morphed it into an English word that describes anything giving off a luminous, rainbow sheen or that changes color in the light.  

Another viewpoint, iridescent is derived from the name of the Greek goddess of the rainbow, Iris, and the Latin suffix '-escent' meaning to have a tendency towards something. 

Examples of iridescent used in a sentence: 
"Adult males have a pink-streaked iridescent throat-patch that can be held erect."
"The drake's head has an iridescent purple sheen when held at a certain angle."
"As she neared the object, she noticed it was an iridescent purple and pink."
"Under the crystal bright light of a full moon their blue marble shined, iridescent." 
"Iridescence, the play of colors like a rainbow, can be seen in various natural and man-made examples, including soap bubbles, oil slicks, and certain minerals."  
"You can also purchase iridescent Christmas bulbs that you can hang from your tree."