Encyclopedias, Almanacs, Transcripts, and Maps
- Ab? Bakr
- Ab? Y?suf
- Abbahu
- Abbaye
- Abbey, Edward Paul (1927 – 1989) American Environmentalist and Writer
- Abélard, Pierre
- Abhinavagupta
- abiotic factors
- Abulafia, Me?ir
- Academy Award
- Academy awards (‘Oscars’) — best film
- Acanthocephala (Thorny Headed Worms)
- Acanthuroidei (Surgeonfishes and Relatives)
- accents
- Accounting for Nature
- Acehnese Religion
- Acid and Base
- Acid Deposition
- Acid Mine Drainage
- Acidification