This definition is wrong.
Pump & Dump:
Massive buying and selling activity of cryptocurrencies (sometimes organized and to one’s benefit ) which essentially result in a phenomenon where significant surge in value of coin followed by a huge crash take place in a short timeframe.
That is what scammers tell the newbies, but here is the real definition:
Pump and dump" (P&D) is a form of securities fraud that involves artificially inflating the price of an owned stock through false and misleading positive statements, in order to sell the cheaply purchased stock at a higher price. Once the operators of the scheme "dump" sell their overvalued shares, the price falls and investors lose their money. This is most common with small cap cryptocurrencies and very small corporations, i.e. "microcaps."