late 14c., "intervening, interposed;" early 15c., "with nothing interposed; direct," also with reference to time, from Old French immediat, from Late Latin immediatus "without anything between," from assimilated form of in- "not, opposite of" (see in-(1)) + mediatus, past participle of mediare "to halve," later, "be in the middle," from Latin medius "middle" (see medial, adj.).