Aa is the name of a large number of small European rivers.
The word is derived from the Old German aha, cognate to the Latin aqua, water (cf. German -ach). In German also Au and Aue exists, similar to å in North Germanic languages, with the meaning of moderately sized river. It is also an English noun, beloved of Scrabble players, meaning a stream.
The following are the more important streams of this name:
- in France:
- in Switzerland:
- in Germany:
- the Westphalian Aa (Westfälische Aa), rising in the Teutoburg Forest, and joining the Werre at Herford.
- the Münster Aa (Münstersche Aa), a tributary of the Ems near Münster.
- the Great Aa (Große Aa), a tributary of the Ems near Lingen.
- and several others (Ahauser Aa, Alstätter Aa, Bocholter Aa, Grenzaa, Ibbenbürener Aa, Speller Aa, Steinfurter Aa).
- in the Netherlands:
- in Latvia: