Songfacts®:

• Cole Porter wrote "It's De-Lovely" for Born To Dance, but it ended up in the 1936 musical Red, Hot And Blue!, performed by Ethel Merman and Bob Hope. It was also featured in the 1956 remake of Anything Goes, where it was sung by Mitzi Gaynor and Donald O'Connor.
• In the George Eells biography of Porter, The Life That He Led, the genesis of the song is attributed to a remark made by his friend Monty Woolley on board a ship in or just off Rio Harbor. Porter was watching the dawn break and said to his wife "It's delightful"; she replied "It's delicious," and Woolley chipped in "It's de-lovely."
  
  Later, Porter told the same story substituting mangosteen melon for the dawn. >>

  Suggestion credit:
  Alexander Baron - London, England, for above 2
• The 2004 movie De-Lovely takes its title from this song. Starring Kevin Kline, the film tells the story of Porter's life. It wasn't the first film to do so. Cary Grant played the composer in a mostly fictionalized 1946 biopic, also named after a Porter song: "Night And Day."
• Robbie Williams performed this song in the film De-Lovely.
• Ethel Merman sang this during her appearance on The Muppet Show. In the season 1 episode, she performs a medley of show tunes, with Scooter and Gonzo joining her on "It's De-Lovely."