1711, "the real point" (of a law case, etc.), from Anglo-French legalese phrases such as cest action gist "this action lies," from Old French gist en "it consists in, it lies in," from gist (Modern French gît), third person singular present indicative of gésir "to lie," from Latin iacet "it lies," from iacere "to lie, rest," related to iacere "to throw" (see jet, v.). Extended sense of "essence" first recorded 1823.