pre·ja·cent I. \prēˈjāsənt\adjective Etymology: Middle French, from Latin praejacent-, praejacens, present participle of praejacēre to lie before, from prae- pre- + jacēre to lie — more at adjacent 1.obsolete: preexisting 2.: being an antecedent proposition in logic from which another is developed II. noun (-s) : a prejacent proposition in logic