The term whale is used to describe a player who has very little poker knowledge but has a big bankroll and likes action.
A poker whale is a step beyond fish. These players’ skills are usually quite low, while their desire to play the game and be in the mix is very high. These are the players that usually get bum-hunted.
Of course, just like a fish, a whale is a derogatory term, so players will usually only use it among themselves and not in the actual presence of the player they consider the whale.