 It is derived from the Anglo-Norman "Jehane" and "Jehanne" (Modern French "Jeanne") which were introduced into Ireland by the Anglo-Normans in the Middle Ages.The name is thus a cognate of the English "Joan", derived from the Latin "Ioanna" and "Iohanna" (modern English "Joanna", "Joanne"), which are in turn from the Greek "Iōanna".This Greek name is a feminine form of the Greek "Iōannēs", which is in turn a shortened form of the Hebrew "Johanan" 

The popularity of the actress Siobhán McKenna (1923–1986) helped the resurgence of the name in the twentieth century.