nicholas-name

noun2

1. •
   (humorous) A longer name corresponding to a shortened version common as a nickname, either of which may be the person or thing's actual name.

   • He always calls me my nicholas-name Josephine, even though I keep telling him JJ is fine.
   • My legal name is Tim, but my nicholas-name is Timothy.
2. •
   (humorous) A familiar name for a person or thing that is used in place of its actual name, usually longer or less wieldy.

   • I'm Kai, but my friends call me Kylesternus. It's a nicholas-name.