Literally, to breathe together (with); breathe in unison or accord, as in singing.To agree by oath, covenant, or otherwise to commit a reprehensible or illegal act; engage in a conspiracy; plot; especially, hatch treason.Figuratively, to concur to one end; act in unison; contribute jointly to a certain result: as, all things conspired to make him prosperous.Synonyms To intrigue. To combine, concur, unite, cooperate.To plot; plan; devise; contrive; scheme for.