DCHP-1 Online
boiler 
n. a stretch of seething water, as in a rapids or below a waterfall.
See also: boil-up (def. 1)
- 1829 When a raft of oak arrives at a water-fall, it has to be dragged past it by oxen or horses on the land; for if allowed to run over as other timber is, when it broke up in the cataract and boilers, it would sink.
- 1889 Right ahead are seen the white seething "boilers" of the rapids.
- 1829 When a raft of oak arrives at a water-fall, it has to be dragged past it by oxen or horses on the land; for if allowed to run over as other timber is, when it broke up in the cataract and boilers, it would sink.