خلافة
Khilāfah
The institution of man as God’s vicegerent on earth, and the government that continued the worldly rule of the Prophet Muhammad (peace be upon him).
What it means
Khilāfah is the noun for the office or institution of the khalīfah. It has two senses. The first is the human responsibility, given by God, to act as His vicegerent on earth (2:30). The second is the government that carried on the worldly leadership of Muhammad (peace be upon him) after his death, beginning with Abu Bakr, then Umar, Uthman and Ali. These four are called the rightly guided caliphs. Later dynasties, including the Umayyads, Abbasids and Ottomans, also held the office. The consultation of the community in choosing and advising its leader is linked in the Quran to the principle of shūrā (42:38).
Often misunderstood as
“Caliphate” in English news writing usually means a state of one ruler; the word in Arabic also names the human duty of stewardship over the earth.
What the sources say
Scholars of the classical period, such as al-Mawardi, wrote works on the office, and they differed on how the khalīfah should be chosen. Muslims today hold different views on whether the institution should be revived.
Term and Arabic as listed in Ismail al Faruqi, Toward Islamic English (International Institute of Islamic Thought, 1995), p. 31, listed as KHILĀFAH. The definition is restated here.