خليفة
Khalīfah
The vicegerent of God in space and time; the word is also used for the successor who leads the Muslim community.
What it means
Khalīfah comes from a root meaning to succeed or to stand in the place of another. The Quran uses it when God tells the angels, “I am placing on the earth a khalīfah” (2:30), and it addresses David with the same word (38:26). In this sense the human being holds the earth as a trust, answerable to God for how it is used. The same word came to mean the leader of the Muslim community after Muhammad (peace be upon him), beginning with Abu Bakr, who was called khalīfat rasūl Allāh, the successor of the Messenger of God. English “caliph” is the usual form of this second sense.
Often misunderstood as
Translating it as “successor” or “caliph” alone loses the Quranic sense of the human being as God’s vicegerent on earth.
What the sources say
The classical commentators differ on who is meant in 2:30: some take it to be Adam and his descendants, and some take it to mean a people who succeed one another. All agree that it describes a responsibility given by God and not a share in His authority.
Term and Arabic as listed in Ismail al Faruqi, Toward Islamic English (International Institute of Islamic Thought, 1995), p. 31, listed as KHALĪFAH. The definition is restated here.