| 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 |