Coaxial warp drive, also known as coaxial induction drive or simply coaxial drive, was a propulsion system that functioned by drawing in subatomic particles and reconfiguring their internal geometries. This allowed a starship the capability to fold the fabric of space, allowing it to travel instantaneously across extremely large distances. (VOY: "Vis à Vis")
In 2374, an experimental coaxial warp ship was piloted by a shapeshifter with the ability to switch their DNA with another individual, in essence, switch bodies. The shapeshifter and their ship was encountered by the crew of the USS Voyager in the Delta Quadrant. At the time, the shapeshifter was pretending to be a Benthan named Steth and claimed that the ship was also of Benthan origin.
Emerging from coaxial space in an unstable condition, the vessel threatened to explode and collapse space within a radius of a billion kilometers. Such an occurance was averted, however, when Tom Paris, Voyager's helmsman, managed to generate a symmetric warp field around the coaxial warp ship, containing the instabilities in the space-folding core. The drive of the craft was imperfect, as particle instabilities tended to overload the engines. To correct for this flaw, Paris conceived of the idea of using a polaric modulator to dilute the particle stream as they entered the coaxial core, drawing inspiration from a 20th century device known as a carburetor.
The Voyager crew eventually discovered that the impostor was not who they claimed to be when he switched places with Captain Janeway, in an attempted to escape from Voyager using a Starfleet Class 2 shuttle modified to use a coaxial warp drive. Paris was able to prevent the escape by targeting the polaric modulator with a chromoelectric pulse, disrupting the shuttle's engines. While the crew now had a coaxial shuttle modified by Dis, no attempts were made to implement the technology for Voyager, presumably the technology was deemed too dangerous. (VOY: "Vis à Vis")