[Fantam]

I think that the term donk is usually used to describe the circumstances in which a bet is made.

A donk bet is typically a bet from a player, who showed no agression on a previous betting round, into the player who did bet on the previous street.

i.e. the player check/calls a flop bet, then bets into the original flop better on the turn.

A fish is the description for a player, who usually plays a high proportion of their hands, seldom bets or raises, but usually calls other players' bets and raises on most streets. Fish like to check and call a lot.

A maniac is the term for a loose agressive player. A maniac likes to play most of their hands, and they enjoy betting and raising on most streets. Some are more agressive than others and they love bluffing with almost hopeless hands in desperate attempts to win big pots, which they have helped to create.