Going back on a promise or bargain. This may be motivated by sheer opportunism: once the other party is committed to a bargain there is a temptation to renege on one's promises. In many cases a reneger will claim either that circumstances have changed, or that the consequences of the bargain are not what they had been led to expect. This is a highly suspect defence: in the nature of things circumstances are never exactly what anybody expected, and it is impossible to describe them exhaustively. It is thus in the essence of a promise or bargain that it should be binding except in the case of extremely radical changes in circumstances, or clear misrepresentation by the other party. General freedom to renege would make impossible many economically efficient bargains, for example those concerning loans and career choice.

• organizational slack
• Organization for Economic Cooperation and Development
• Organization of Petroleum Exporting Countries
• organized labour
• organized sector
• origin
• oscillation
• oscillatory function
• other things being equal
• outcry, open
• outflow, capital
• outlier
• output
• output-capital ratio
• output effect
• output-input
• output method
• output per hour worked
• output per manhour
• outside money
• outsiders and insiders
• outsourcing
• over-capacity working
• overdraft
• overfull employment