Mid 19th century (originally dialect): probably the second element of fidfad, contraction of fiddle-faddle. Compare with faddy.

• fiddle from Old English:

  In Old English fiddle was the usual word for a stringed instrument like a violin, based on Latin vitulari ‘to celebrate, be joyful’, which may come from Vitula, the name of a Roman goddess of joy and victory. In the sense ‘to swindle’ fiddle was first used in the 1630s. The connection with the instrument probably came from the idea that the ‘fiddler’ or player could make people ‘dance to his tune’. Expressions like fiddle-de-dee and fiddle-faddle, meaning ‘nonsense’, come from the idea of violin-playing being a trivial or pointless exercise, and in turn fiddle-faddle is the origin of fad.

  When we criticize someone for concerning themselves with trivial affairs while ignoring serious matters, we may say that they are fiddling while Rome burns. This looks back to a story about the Roman emperor Nero. According to one historian, when Rome suffered from a disastrous fire Nero reacted by singing a song about the fall of Troy and accompanying himself on some instrument—not a fiddle, which had not been invented then. To play second fiddle is to take a less important role. The idea here is that you are there to support the person taking the leading part.