Caliph – The English version of the Arabic phrase, khalifa, which means vice-regent or trusted guardian. It was the title referred to the successor of Prophet Muhammad, Abu Bakr, as the political ruler of all Muslims and therefore in charge of the Caliphate, the traditional form of Islamic governance. The title of Caliph was held by Sunni rulers till the last Turkish Ottoman Caliph in 1924. In 2014, the Irhabi group, Daesh, proclaimed a new caliphate, which was met with great opposition and derision by Muslims globally, and has become a moot point since the group’s subsequent territorial collapse. It should be capitalised, especially before a name when used as the formal title for a historic Muslim leader or ruler who legitimately held the title.
