dunk tank

dunk tank (plural dunk tanks)

1. A large tank of water, over which a dunk seat is suspended, which seat can be made to tip or fall into the tank of water, thus dunking whoever is sitting on the seat. It is used as an attraction mainly used in funfairs.
2. Any open-topped tank used for dunking. (Can we add an example for this sense?)

• ducking stool
• dunking booth
• dunking machine