A temporal shift is an event in which a person or thing is transported from their time to another point within the space-time continuum.
An example of such a phenomenon occurred in 2371, on stardate 48579.4, in the Delta Quadrant. The crew of the Federation starship USS Voyager detected a wormhole, which they used to make contact with Romulan scientist Telek R'Mor in the Alpha Quadrant. R'Mor eventually agreed to beam over to Voyager and back to his vessel, stating that he would arrange a transport vessel to take the lost crew back home. However, upon arrival, Lieutenant Tuvok realized that the wormhole was a bridge through time as well as space, and that Telek R'Mor was actually from 2351, twenty years in the past. (VOY: "Eye of the Needle")