"Aye, it's a ship. TARDIS is just the name for it."

There was more to it then that, but rather than confuse things further, Jamie simply decides to leave that part of it be apart from giving Inessa an apologetic look.

"Sorry, I've lost track of who I've told that to. But my point was that the Doctor'd usually want to leave after we helped someone, so even when there were parties we'd not stick around at them for very long. Makes this a different experience for sure."