What is the Full Form of DJ ?

DJ - Disc Jockey

Disc Jockey is a person who play music for the audience of a Party, Pub or Disco.  Disc Jockey's can play the original music or make use of a mixer to change its complete music and lyrics. Disc Jockey has a complete control over the music getting played in the hall.

The name Disc Jockey came from "Compact disc" (an optical storage medium for songs and data) which are usually used by the DJ's to play songs.