Named to always appear first in alphabetical listings; or alternatively after Pieter van der Aa.
- Aa (plant) on Wikipedia.Wikipedia:Aa (plant)
- Aa (Orchidaceae) on Wikispecies. Wikispecies: Aa (Orchidaceae)
From Proto-Germanic *ahwō (“waters, river”), from Proto-Indo-European *h₂ekʷeh₂ (“water”); both natively, and through Dutch Low Saxon Aa and German Low German Aa (both from Old Saxon aha (“stream”)), and German Aa (from Old High German aha (“stream”)). For more information, see the English cognate ea.
- the name of many small rivers and streams