noun[ C ]geographyspecializeduk/ˈəʊ.və.fɔːl/us/ˈəʊ.vɚ.fɑːl/
（由于水下的凸起或水流的交汇而形成的）异常汹涌的水域
an area of very rough water caused by a raised area in the ground under the water, or by the meeting of two currents (= movements of water in a particular direction)
The water can throw up great overfalls, which small boats should try to avoid.水中会出现异常汹涌的水域，小船应尽量避开。
更多例句
The overfalls are huge and very dangerous.
The sea was white from the massive overfalls.
With its fierce currents and overfalls, this stretch of water is difficult to sail through.
The area is notorious for its tidal overfalls and treacherous reefs.