An aeroshuttle was a runabout-like spacecraft embedded in the saucer underside of Intrepid-Class Starships.
In 2376 Dala and Zar, posing as Captain Kathryn Janeway and Chakotay showed Varn a schematic of the USS Voyager which identified its aeroshuttle. (VOY: “Live Fast and Prosper”) A graphic of an aeroshuttle also appeared in Daniels’ database while it was being viewed by Captain Archer and T’Pol in 2152. (ENT: “Future Tense”)
The aeroshuttle was initially not represented on Voyager’s master systems display as devised by Doug Drexler, seen in the early episodes, but showed up in the graphic from “Phage” onward. Drexler clarified, “I drew the original MSD for the back of the bridge. After that, Wendy cut and pasted it to suit episode specific situations,” to which designer Rick Sternbach half jokingly added, “The screenshots that do show the AeroShuttle (outline or filled) seem to be of the early shape that I can only describe as looking like George Jetson’s flying car. I don’t believe the true elevation was ever inserted into the cutaway art.
Via Memory Alpha