a. [f. L. contrā adv. + -plex -fold, as in simplex, duplex, etc.] Telegr. Having two currents or messages passing in opposite directions at the same time.
1879. Prescott, Sp. Telephone, 346. The terms contraplex and diplex are here applied as specific names for designating clearly the way in which the particular simultaneous double transmission … is effected.
