| 0 | A | B | C | D | E |
| F | G | H | I | J | K |
| L | M | N | O | P | Q |
| R | S | T | U | V | W |
| X | Y | Z | # | ||
| a | the first letter of the English alphabet | ||
| a | ampere (Units & Measurements) adenine (Biochemistry) mass number (Physics) 10 (hexadecimal notation) 6th note in C major (music) highest grade (education) one of the human blood types (Medicine) | ||
| a to b | from one place to another | ||
| a to z | all the way from the beginning to the end | ||
| Ablutophobia | fear of washing or bathing (see list of phobias) | ||
| Acanthochronology | study of cactus spines grown in time ordered sequence (see list of branches of science) | ||
| Acarology | study of mites and ticks (see list of branches of science) | ||
| Acarophobia | fear of itching or of the insects that cause itching (see list of phobias) | ||
| Aceology | study of remedies, or of therapeutics (see list of branches of science) | ||
| Acerophobia | fear of sourness (see list of phobias) | ||
| Achluophobia | fear of darkness (see list of phobias) | ||
| Acology | study of medical remedies (see list of branches of science) | ||
| Acousticophobia | fear of noise (see list of phobias) | ||
| Acoustics | study of sound (see list of branches of science) | ||
| Acrophobia | fear of heights (see list of phobias) | ||
| Actinobiology | study of the scientific principles, mechanisms, and effects of the interaction of ionizing radiation with living matter (see list of branches of science) | ||
| Adenology | study of glands (see list of branches of science) | ||
| Aedoeology | study of generative organs (see list of branches of science) | ||
| Aeroacrophobia | fear of open high places (see list of phobias) | ||
| Aerobiology | study of airborne organisms (see list of branches of science) | ||
| Aerodonetics | study of gliding (see list of branches of science) | ||
| Aerodynamics | study of movement in a flow of air or gas (see list of branches of science) | ||
| Aerolithology | study of aerolites; meteorites (see list of branches of science) | ||
| Aerology | study of the atmosphere (see list of branches of science) | ||
| Aeronausiphobia | fear of vomiting secondary to airsickness (see list of phobias) | ||
| Aeronautics | study of navigation through air or space (see list of branches of science) | ||
| Aeropalynology | study of pollens and spores in atmosphere (see list of branches of science) | ||
| Aerophobia | fear of aircraft or flying (see list of phobias) | ||
| Aerostatics | study of air pressure; art of ballooning (see list of branches of science) | ||
| Agateophobia | fear of insanity (see list of phobias) | ||
| Agliophobia | fear of pain (see list of phobias) | ||
| Agnoiology | study of ignorance (see list of branches of science) | ||
| Agoraphobia | fear of open spaces (see list of phobias) | ||
| Agraphobia | fear of sexual abuse (see list of phobias) | ||
| Agriology | study of primitive peoples (see list of branches of science) | ||
| Agrizoophobia | fear of wild animals (see list of phobias) | ||
| Agrobiology | study of plant nutrition; soil yields (see list of branches of science) | ||
| Agroecology | study of ecological processes applied to agricultural production systems (see list of branches of science) | ||
| Agrogeology | study of agrominerals (see list of branches of science) | ||
| Agrology | study of agricultural soils (see list of branches of science) | ||
| Agronomics | study of productivity of land (see list of branches of science) | ||
| Agrostology | study of grasses (see list of branches of science) | ||
| Agyrophobia | fear of streets or crossing the street (see list of phobias) | ||
| Aichmophobia | fear of needles or pointed objects (see list of phobias) | ||
| Ailurophobia | fear of cats (see list of phobias) | ||
| Akousticophobia | fear of sound (see list of phobias) | ||
| Albuminurophobia | fear of kidney disease (see list of phobias) | ||
| Alektorophobia | fear of chickens or ducks (see list of phobias) | ||
| Alethiology | study of truth (see list of branches of science) | ||
| Algedonics | study of pleasure and pain (see list of branches of science) | ||
| Algology | study of algae (see list of branches of science) | ||
| Algology | study of pain (see list of branches of science) | ||
| Algophobia | fear of pain (see list of phobias) | ||
| Alliumphobia | fear of garlic (see list of phobias) | ||
| Allodoxaphobia | fear of opinions (see list of phobias) | ||
| Altophobia | fear of heights (see list of phobias) | ||
| Amakaphobia | fear of carriages (see list of phobias) | ||
| Amathophobia | fear of dust (see list of phobias) | ||
| Amaxophobia | fear of riding in a car (see list of phobias) | ||
| Ambulophobia | fear of walking (see list of phobias) | ||
| Amnesiphobia | fear of amnesia (see list of phobias) | ||
| Amychophobia | fear of scratches or being scratched (see list of phobias) | ||
| Anablephobia | fear of looking up (see list of phobias) | ||
| Anaesthesiology | study of anaesthetics (see list of branches of science) | ||
| Anatidaephobia | fear of chickens (see list of phobias) | ||
| Anatomy | study of the structure of the body (see list of branches of science) | ||
| Ancraophobia | fear of wind (see list of phobias) | ||
| Andragogy | study of educating of adults (see list of branches of science) | ||
| Andrology | study of men's physiology (see list of branches of science) | ||
| Androphobia | fear of men (see list of phobias) | ||
| Anemology | study of wind (see list of branches of science) | ||
| Anemophobia | fear of air drafts or wind (see list of phobias) | ||
| Anginophobia | fear of angina, choking or narrowness (see list of phobias) | ||
| Angiology | study of blood flow and lymphatic system (see list of branches of science) | ||
| Anglophobia | fear of England or English culture (see list of phobias) | ||
| Angrophobia | fear of anger or of becoming angry (see list of phobias) | ||
| Ankylophobia | fear of immobility of a joint (see list of phobias) | ||
| Anthophobia | fear of flowers (see list of phobias) | ||
| Anthrophobia | fear of flowers (see list of phobias) | ||
| Anthropobiology | study of human biology (see list of branches of science) | ||
| Anthropology | study of human cultures (see list of branches of science) | ||
| Anthropophobia | fear of people or society (see list of phobias) | ||
| Anthrozoology | study of human-animal interaction (see list of branches of science) | ||
| Antlophobia | fear of floods (see list of phobias) | ||
| Anuptaphobia | fear of staying single (see list of phobias) | ||
| Apeirophobia | fear of infinity (see list of phobias) | ||
| Aphenphosmphobia | fear of being touched (see list of phobias) | ||
| Apiology | study of bees (see list of branches of science) | ||
| Apiphobia | fear of bees (see list of phobias) | ||
| Apotemnophobia | fear of persons with amputations (see list of phobias) | ||
| Aquaphobia | fear of water (see list of phobias) | ||
| Aquatic ecology | study of aquatic environment (see list of branches of science) | ||
| Arachibutyrophobia | fear of peanut butter sticking to the roof of the mouth (see list of phobias) | ||
| Arachnephobia | fear of spiders (see list of phobias) | ||
| Arachnology | study of arachnids (see list of branches of science) | ||
| Arachnophobia | fear of spiders (see list of phobias) | ||
| Archaeology | study of human material remains (see list of branches of science) | ||
| Archelogy | study of first principles (see list of branches of science) | ||
| Archology | study of the origins of government (see list of branches of science) | ||
| Areology | study of Mars (see list of branches of science) | ||
| Aretaics | science of virtue (see list of branches of science) | ||
| Aristology | study of dining (see list of branches of science) | ||
| Arithmophobia | fear of numbers (see list of phobias) | ||
| Aromachology | study of smell and odor (see list of branches of science) | ||
| Arrhenphobia | fear of men (see list of phobias) | ||
| Arrhenphobia | fear of men (see list of phobias) | ||
| Arsonphobia | fear of fire (see list of phobias) | ||
| Arthrology | study of joints (see list of branches of science) | ||
| Arthropodology | study of arthropods like insects and arachnids (see list of branches of science) | ||
| Astacology | science of crayfish (see list of branches of science) | ||
| Asteroseismology | study of star oscillations (see list of branches of science) | ||
| Astheniology | study of diseases of weakening and aging (see list of branches of science) | ||
| Asthenophobia | fear of fainting or weakness (see list of phobias) | ||
| Astraphobia | fear of thunder and lightning (see list of phobias) | ||
| Astrapophobia | fear of thunder and lightning (see list of phobias) | ||
| Astrobiology | study of extraterrestrial life (see list of branches of science) | ||
| Astrobotany | study of plants in space (see list of branches of science) | ||
| Astrodynamics | study of motion of rockets and spacecraft (see list of branches of science) | ||
| Astrogeology | study of extraterrestrial geology (see list of branches of science) | ||
| Astronomy | study of celestial bodies and phenomena (see list of branches of science) | ||
| Astrophobia | fear of stars or celestial space (see list of phobias) | ||
| Astrophysics | study of behaviour of interstellar matter (see list of branches of science) | ||
| Asymmetriphobia | fear of asymmetrical things (see list of phobias) | ||
| Ataxiophobia | fear of the loss of bodily control or muscular coordination (see list of phobias) | ||
| Ataxophobia | fear of disorder or untidiness (see list of phobias) | ||
| Atelophobia | fear of imperfection (see list of phobias) | ||
| Atephobia | fear of ruin or ruins (see list of phobias) | ||
| Athazagoraphobia | fear of being forgotten or ignored or forgetting (see list of phobias) | ||
| Atmology | study of aqueous vapor (see list of branches of science) | ||
| Atomosophobia | fear of atomic explosions (see list of phobias) | ||
| Atychiphobia | fear of failure (see list of phobias) | ||
| Audiology | study of hearing (see list of branches of science) | ||
| Aulophobia | fear of flutes (see list of phobias) | ||
| Aurophobia | fear of gold (see list of phobias) | ||
| Auroraphobia | fear of northern lights (see list of phobias) | ||
| Autecology | study of ecology of one species (see list of branches of science) | ||
| Autodysomophobia | fear of vile odor (see list of phobias) | ||
| Autology | study of oneself (see list of branches of science) | ||
| Automatonophobia | fear of human-like figures (see list of phobias) | ||
| Automysophobia | fear of being dirty (see list of phobias) | ||
| Autophobia | fear of being alone or isolation (see list of phobias) | ||
| Auxology | study of growth (see list of branches of science) | ||
| Aviatophobia | fear of flying (see list of phobias) | ||
| Avionics | study of electronic devices for aircraft (see list of branches of science) | ||
| Aviophobia | fear of flying (see list of phobias) | ||
| Axiology | study of the ultimate nature of value (see list of branches of science) | ||
| 0 | A | B | C | D | E |
| F | G | H | I | J | K |
| L | M | N | O | P | Q |
| R | S | T | U | V | W |
| X | Y | Z | # | ||