a tranche of something - a piece, section, or part of it. A tranche of things is a group of them; a formal use, one of series of instalments (used when referring to loans to companies, government securities which are issued over a period of time, or money withdrawn by a country from the I.M.F.), a part of a sum of money, such as a loan or payment, e.g. the gold tranche, that part of a country's I.M.F. quota that had once been paid in gold