1. A pool.
2. (Science: engineering) a reservoir and sluiceway beside a navigable stream, just above a shoal, so that the stream may pour in water as boats pass, and thus bear them over the shoal.
(Science: mechanics) flash wheel, a paddle wheel made to revolve in a breast or curved water way, by which water is lifted from the lower to the higher level.
Origin: oe. Flasche, flaske; cf. OF. Flache, f. Flaque.