- A Chronicle of Ming Dynasty
- A Chronicle of Opera, From 1644 to 1911: Performed at the Qing Court
- A Chronological History of the Ten Reigns of the Song Dynasty
- A Chronological Record of Calligraphies and Paintings from the Dream Garden
- A. Church
- A. Church (1903—1995)
- Achutan Ramachandran
- ACI
- acibenzolar-S-methyl
- aciclovir
- acicular crystal
- aciculisilva
- acid
- Acidalia Planitia
- acid amides poisoning
- acid anhydride
- acid-base balance of body fluid
- acid base buffer solution
- acid-base buffer solution
- acid base catalysis
- acid-base catalysis
- acid-base catalyst
- acid base equilibrium
- acid-base equilibrium
- acid-base equilibrium disturbance