JIC fittings stand for Joint Industry Council Thread and are a type of metal to metal sealing type of fitting with a 37° flare.  JIC design specifications come from the Society of Automotive Engineers (SAE) as defined by SAE J514 and MIL-DTL-18866 standards.  JIC fittings are widely used in fluid power and fuel delivery applications where high pressure up to 10,000 psi exists.

Source: Wikipedia