Aa (1)

by practicalspactical

[from the OED]

Obs.

[prob. a. ON. á, cogn. w. OE. éa, Goth. ahwa, L. aqua; see also Æ, and EA.] 

A stream, a water-course.

1430 Munim. Magd. Coll. Oxf. No. 7 A. (Saltfleetby, Linc.) Communis sewere vocat’ le Seventowne Aa.