Term "dump" has come to the world of cryptocurrency from fiat currencies and assets trading and is more applicable to trading on the stock exchange, but it also useful for passive investors. Dump refers to the situation when some dishonest cryptocurrency market player artificially reduces the cost of cryptocurrency to the price he/she needs and buys it at a much lower cost.
For example, imagine you have a very-very large amount of Bitcoin cryptocurrency and you start to sell it quickly so that cryptocurrency market gets large amount of Bitcoins and the demand for it falls temporarily and thereafter the price also falls. At a certain point, when the exchange rate fell to the mark you need, you buy back your Bitcoins at a fallen and much more profitable price.
