Singularity
A gravitational singularity is a point in space where the force of gravity (as measured by the curvature of spacetime or the density of matter) becomes infinite. The typical example of a singularity is the point in space at the center of a black hole.
Singularities in Science Fiction
Singularities are occasionally used as weapons[1] or power sources[2] in science fiction. Star Trek tends to refer to them as "quantum singularities".
Romulan starships
Romulan starships, including the D'deridex-class Warbird, use an artificial quantum singularity to power the ship. This means that Romulan starships don't experience the hazards of carrying antimatter fuel for a warp core, but the quantum singularity would have safety issues of its own, since an uncontrolled singularity would consume a starship. Apparently some alien life forms use singularities as breeding grounds, and this can interfere with the operation of the Romulan power system.[3]