gist (n.) Look up gist at Dictionary.com
1711, "the real point" (of a law case, etc.), from Anglo-French legalese phrases such as cest action gist "this action lies," meaning "this case is sustainable by law," from Old French gist en "it consists in, it lies in" (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.