A large auxiliary craft designed to dock in the underside of the saucer of Intrepid-class ships such as Voyager, visible on the model throughout the series but never launched or named on screen.
The Aeroshuttle is the craft that sits in the round fitting beneath the forward hull of the USS Voyager. The designer Rick Sternbach intended it as an atmosphere-capable runabout that could separate from the ship, in the same spirit as the captain's yacht of the Enterprise-D.
It is never used in Star Trek: Voyager and never mentioned in dialogue; the name comes from production material and reference books. Visual effects artists prepared a test sequence showing it launching, but the idea was not taken up.
When the writers wanted a tougher, larger shuttle for the crew, they had Tom Paris design and build the Delta Flyer instead, in Extreme Risk. That left fans to wonder why Voyager, short of shuttles and seventy thousand light years from home, never used the craft that was apparently there all along.