| Acarology | Study of mites | 
        
      | Accidence | Grammar book; science of inflections in grammar | 
        
      | Aceology | Therapeutics | 
        
      | Acology | Study of medical remedies | 
        
      | Acoustics | Science of sound | 
        
      | 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 | 
        
      | Aerolithology | Study of aerolites; meteorites | 
        
      | Aerology | Study of the atmosphere | 
        
      | Aeronautics | Study of navigation through air or space | 
        
      | Aerophilately | Collecting of air-mail stamps | 
        
      | Aerostatics | Science of air pressure; art of ballooning | 
        
      | Agonistics | Art and theory of prize-fighting | 
        
      | Agriology | The comparative study of primitive peoples | 
        
      | Agrobiology | Study of plant nutrition; soil yields | 
        
      | Agrology | Study of agricultural soils | 
        
      | Agronomics | Study of productivity of land | 
        
      | Agrostology | Science or study of grasses | 
        
      | Alethiology | Study of truth | 
        
      | Algedonics | Science of pleasure and pain | 
        
      | Algology | Study of algae | 
        
      | Anaesthesiology | Study of anaesthetics | 
        
      | Anaglyptics | Art of carving in bas-relief | 
        
      | Anagraphy | Art of constructing catalogues | 
        
      | Anatomy | Study of the structure of the body | 
        
      | Andragogy | Science of teaching adults | 
        
      | Anemology | Study of winds | 
        
      | Angelology | Study of angels | 
        
      | Angiology | Study of blood flow and lymphatic system | 
        
      | Anthropobiology | Study of human biology | 
        
      | Anthropology | Study of human cultures | 
        
      | Aphnology | Science of wealth | 
        
      | Apiology | Study of bees | 
        
      | Arachnology | Study of spiders | 
        
      | Archaeology | Study of human material remains | 
        
      | Archelogy | The study of first principles | 
        
      | Archology | Science of the origins of government | 
        
      | Arctophily | Study of teddy bears | 
        
      | Areology | Study of mars | 
        
      | Aretaics | The science of virtue | 
        
      | Aristology | The science or art of dining | 
        
      | Arthrology | Study of joints | 
        
      | Astacology | The science of crayfish | 
        
      | Astheniology | Study of diseases of weakening and aging | 
        
      | Astrogeology | Study of extraterrestrial geology | 
        
      | Astrology | Study of influence of stars on people | 
        
      | Astrometeorology | Study of effect of stars on climate | 
        
      | Astronomy | Study of celestial bodies | 
        
      | Astrophysics | Study of behaviour of interstellar matter | 
        
      | Astroseismology | Study of star oscillations | 
        
      | Atmology | The science of aqueous vapour | 
        
      | Audiology | Study of hearing | 
        
      | Autecology | Study of ecology of one species | 
        
      | Autology | Scientific study of oneself | 
        
      | Auxology | Science of growth | 
        
      | Avionics | The science of electronic devices for aircraft | 
        
      | Axiology | The science of the ultimate nature of values |