Whale
A person or entity holding such a large amount of a given cryptocurrency that its transactions can noticeably affect the price.
A whale is a colloquial term for an investor — an individual, fund, or company — who holds such a large amount of a given cryptocurrency that a single transaction involving them (a large sale or purchase) can noticeably affect the price, especially when market liquidity is lower.
The movements of large wallets are tracked by analytics services (so-called whale tracking/whale alerts) and treated by some traders as a signal for their own investment decisions, although the mere movement of funds between wallets owned by the same person (e.g., a transfer to a different exchange) doesn't necessarily mean a sale.
Related terms
HODL
Slang for the strategy of holding a cryptocurrency long-term regardless of price fluctuations, originating from a typo of the word "hold."
Liquidity
The ease with which an asset can be bought or sold without significantly affecting its price.
Slippage
The difference between the expected and actually executed price of a transaction, resulting from a price change or low market liquidity.