Question about ThirdPersonController.js

I am using the standard third person controller that comes with unity and i am trying to modify it to meet my needs. I was wondering though what does the inAirVelocity variable do?

An example of a line of code where this variable appears in the script is:
var movement = moveDirection * moveSpeed + Vector3 (0, verticalSpeed, 0) + inAirVelocity;


I believe it refers to the how fast you can move left or right if you jump from a standing position. If you jump then push left or right how fast you move in that direction as opposed to jumping WHILE already moving left or right. If that makes sense.