Question: What is 14J?
The term "14J" was first introduced in Episode 4x9, The Shape of Things to Come.
Answer: 14J is the code for a intruder inside the sonic fence. When Sawyer, Hurley, and Locke were in Ben's house, the phone rang and the recorded voice repeated, "14J". Alex had tripped the alarm when Keamy made her turn off the sonic fence (Ep: 4x9, The Shape of Things to Come).
In 1977, when Sayid got inside the fence, Miles came to Sawyer to tell him there was a 14J (Ep: 5x9, Namaste).
