from
The Collaborative International Dictionary of English v.0.48
Flash \Flash\, n. [OE. flasche, flaske; cf. OF. flache, F.
flaque.]
1. A pool. [Prov. Eng.] --Haliwell.
[1913 Webster]
2. (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.
[1913 Webster]
{Flash wheel} (Mech.), 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.
[1913 Webster]