(1) The essence of a thing as meaning that by being which a thing is what it is. As when we say that a rational animal is the haqiqah of a human being. (See Kitabu ‘l-Ta’rifat.)
(2) A word or phrase used in its proper or original sense as opposed to that which trope or figure.
(3) The sixth stage in the mystic journey of the Sufi when he is supposed to receive a revelation of the true nature of the God-head, and to have arrived at “the Truth.”
Based on Hughes, Dictionary of Islam