Repeatability, according to a British Standard definition, "is the ability of a measuring instrument to give identical indications, or responses, for repeated applications of the same value of the measured quantity under stated conditions of use. If an accuracy is the ability of the device or an instrument to tell the truth about the process parameters, the repeatability is the ability of an instrument to stick the same story.
Instruments as well as people are sometimes capable to tell the same lie over and over again. Good repeatability is no guarantee of good accuracy, although poor repeatability is a sure sign of poor accuracy. In other words, good repeatability is a necessary, but not sufficient condition of good accuracy."