The term is immaterial. These costs do cascade through the economy (as they are passed to the next level in the form of a higher price,) and they do accumulate (as they add up, ultimately to paid by the consumer at the final retail stage.) Call them whatever you want.
The real issue is their cumulative magnitude ... While we agree that they exist, IMHO, the FairTax proponents overstate the actual magnitude of these costs.
The term is immaterial.I believe the term is material. "Accumulating" is an additive process, "cascading" is a multiplicative process. A tax that accumulates adds up as the product goes from level to level but the effective tax rate on the base does not change because the tax isn't taxing the tax from previous levels. A cascading tax does tax the tax from previous levels (e.g., a sales tax is imposed on the manufacturer and again on the distributor) so the effective tax rate increases from level to level.