For me a whale refere to someone who own a certain quantity of the total supply of a coin. For bitcoin it should be around 0.1% which is 21K Bitcoin (16.7K with the actual circulating supply), for altcoin it's more around 2% to 20% of total supply so they can manipulate the market like a lot of ICO scam, ninja instamine or airdrop scam... (/s it's all for the futur work of the dev team, they need to eat you know,  )