Teraphasic coil
From Memory Alpha, the free Star Trek reference.
A teraphasic coil was a type of warp coil utilized by the Xyrillians in the early 22nd century.
In 2151, the Enterprise (NX-01) encountered a cloaked Xyrillian starship using the ship's plasma exhaust to replenish their vessel's teraphasic coils, which were damaged. Commander Charles Tucker assisted the Xyrillians in repairing the coils, only for them to break down six days later. (ENT: "Unexpected")
