DARDIS

A DARDIS was a dimensionally transcendental space-time vessel created by the Daleks so that they could chase the Doctor through time and space. One of these craft enabled the Doctor's companions Ian Chesterton and Barbara Wright to return home. The Doctor set the ship for self-destruction after it had transported them to 1965 London (DW: The Chase)

The Daleks and Mavic Chen used a DARDIS to pursue the Doctor, his companions and the Monk. (DW: The Daleks' Master Plan)

The Master obtained a "DARDIS core". (PDA: The Quantum Archangel)

Possibly apocryphal information
One account says that the Daleks used taranium to power their space-time craft. (DWN: Doctor Who — The Chase)

Behind the Scenes
The name DARDIS does appear in scripts for The Chase but not onscreen. The source of the acronym DARDIS remains unknown.