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")
Another variation is a static warp shell, in which a warp shell is deployed around a vessel but not used to accelerate it. The USS Enterprise-D, in three different timelines, used such fields to repair tears in anti-time in the Devron system. (TNG: "All Good Things...")