dark money

noun

US politics

: money contributed to nonprofit organizations (especially those classified as social welfare organizations and business leagues) that is used to fund political campaigns without disclosure of the donors' identities

When it comes to the corrosive influence of money in politics, the 2012 campaign has presented a trifecta of troubling developments. They are, in ascending order of worry: the complete collapse of the presidential public financing system set up in the wake of Watergate; the explosion of the super PAC political committees, which are allowed to take unlimited checks to finance independent expenditures for or against particular candidates; and the proliferation of "dark money," or spending by nonprofit organizations and trade groups that, unlike super PACs, are excused from having to reveal their donors.—