Tethered Aerial Release Developed In Style

The Tethered Aerial Release Developed In Style (abbreviated TARDIS), unlike its namesake, was a hot-air balloon owned by Jackson Lake while he was under the impression he was the Doctor. As the Tenth Doctor noted, its creation was nothing short of sheer brilliance that Jackson Lake already possessed.

When piloted by the Tenth Doctor, Lake's "TARDIS" was key in the destruction of the CyberKing. (TV: The Next Doctor)

Behind the scenes
This is not the only alternative definition for the acronym "T.A.R.D.I.S", the Twelfth Doctor would provide another such example: Totally And Radically Driving In Space. (TV: The Zygon Inversion)