Encyclopædia Britannica, Ninth Edition/Aa

For other versions of this work, see Aa (Encyclopædia Britannica).

Aa, the name of about forty small European rivers. The word is derived from the old German aha, cognate to the Latin aqua, water. The following are the more important streams of this name:—a river of Holland, in North Brabant, which joins the Dommel at Bois-le-Duc; two rivers in the west of Russia, both falling into the Gulf of Livonia, near Riga, which is situated between them; a river in the north of France, falling into the sea at Gravelines, and navigable as far as St Omer; and a river of Switzerland, in the cantons of Lucerne and Aargau, which carries the waters of Lakes Baldeker and Hallwyler into the Aar.