What is your definition of a whale? How many BTCs do you need to have to be a whale?
When we talk about its real meaning, Whale is a mammal that lives in water. But in terms of cryptocurrency, whale is the person who holds a lot of coins. They are one of the reason why market is sometimes dump or pump. Because whales are huge investors, they can manipulate the market whereas small investors are trapped and panic sellers lose a lot of money.