- acarology
- study of mites
- accidence :
- grammar book; science of inflections in grammar
- aceology
- therapeutics
- acology
- study of medical remedies
- adenology
- study of glands
- aedoeology
- science of generative organs
- aerobiology
- study of airborne organisms
- aerodonetics
- science or study of gliding
- aerodynamics
- dynamics of gases; science of movement in a flow of air or gas
