Subspace bubble is a term used for describing the effect of enclosing an object in a subspace field.
There are several forms of subspace fields that can be created around a vessel. One such variation was used by Miles O'Brien to lower the inertial mass of Deep Space 9 so that the station's thrusters could push the station towards the Bajoran wormhole faster, before Cardassian forces claimed it. (DS9: "Emissary")
A subspace bubble can be formed around a person. This variation was used by Seska on a Kazon raider to bypass a force field, in order to retrieve a Federation replicator that she had traded in turn for a Kazon-Federation alliance. (VOY: "State of Flux")
A subspace bubble may form around starships near an exploding microsingularity. The surge of temporal energy that creates the bubble acts as temporal shielding, protecting the ship from changes in the timeline. Such a bubble formed around the USS Defiant, in 2371, while it was orbiting Earth.(DS9: "Past Tense, Part I")