Word Study
leat
CIDE DICTIONARY
leat, n. [Cf. Lead to conduct.].
An artificial water trench, esp. one to or from a mill. C. Kingsley. [1913 Webster]
OXFORD DICTIONARY
leat, n. Brit. an open watercourse conducting water to a mill etc.
Etymology
OE -gel{aelig}t (as Y- + root of LET(1))
For further exploring for "leat" in Webster Dictionary Online