The Jurisprudential Definition of Gharar (Risk-taking) from the Point of View of Shia Jurists

According to a narration of the Holy Prophet and the consensus of the jurists of the two major denominations (of Shi’a and Sunni), "gharar" (risk-taking) is known as one of the reasons for the invalidity of transactions. But what is the nature of gharar?
Despite its importance, there are few researchers who have studied its truth and definition; This research has tried to determine the nature of gharar by gathering different views on the definition of gharar and providing a detailed analysis of its application in jurisprudence. This research has been able to compile the sayings of the jurists in description of gharar and by providing an analysis of its application in jurisprudence, to determine the genus and nature differentia of gharar, "sale", "barters" (mu’āwiḍāt), as well as the point of view of jurists about the differentia of gharar in cases such as "impossibility to measure" or "non-safety of annihilation before deliverance" or "leading to the conflict" or "complicated and confused things" or "having risk" or "Something that its attainment is unknown" or "something that its access or its amount is unknown" or " deserving to be avoided by custom" or "its attainment being unknown". From the point of view of this research the jurisprudential definition of gharar according to the practical method of jurists is as follows: "Every exchange and anything related to it in which the existence, occurrence or value of one of the two substitutes is unknown." The result of this research will be used in the more precise implementation of the rule in jurisprudence issues and will be cited as a dynamic rule.