(billiards, snooker, pool) To cause (a ball) to rebound from a cushion before entering the pocket.
(intransitive) (followed by for) To act as substitute.
(intransitive) To go or march at twice the normal speed.
(transitive) To multiply the strength or effect of by two.
(military) To unite, as ranks or files, so as to form one from each two.
(radio, informal, of a station) To transmitsimultaneously on the same channel as another station, either unintentionally or deliberately, causing interference.