| $A | Australian Dollars 
| Others |
| @a | All Players
| Others |
| A | A-check
| Others |
| A | Aakash
| Others |
| A | Absolute
| Others |
| A | Absorbance
| Others |
| A | Absorptivity
| Others |
| A | Acceleration
| Others |
| A | Accelerations
| Others |
| A | Accept
| Others |
| A | Accessory
| Others |
| A | Accord
| Others |
| A | Account
| Others |
| A | Accusative
| Others |
| A | Ace
| Others |
| A | Acetum
| Others |
| A | Act
| Others |
| A | Actin
| Others |
| A | Actinomyces
| Others |
| A | Active
| Others |
| A | Activism
| Others |
| A | Activity
| Others |
| A | Actor
| Others |
| A | Add
| Others |
| A | Address
| Others |
| A | Adenine
| Others |
| A | Adenosine
| Others |
| A | Adjective
| Others |
| A | admittance Electricity
| Others |
| A | Adrenaline
| Others |
| A | Adriamycin
| Others |
| A | Adult
| Others |
| A | Adults & Communities
| Others |
| A | Advanced
| Others |
| A | Adventure Mode
| Others |
| A | Aedes
| Others |
| A | African
| Others |
| A | Aft
| Others |
| A | Against
| Others |
| A | Agar
| Others |
| A | Ages
| Others |
| A | Agilent Technologies Incorporated
| Others |
| A | Agiliance
| Others |
| A | Air Force Training Category
| Others |
| A | Akinetic
| Others |
| A | Aktopia
| Others |
| A | Alanine
| Others |
| A | Albino guinea pig
| Others |
| A | Alcohol
| Others |
| A | Alex
| Others |
| A | All lines
| Others |
| A | Allele
| Others |
| A | Allergist
| Others |
| A | Allergy
| Others |
| A | Alpha
| Others |
| A | Alternative
| Others |
| A | Alton Railroad
| Others |
| A | alveolar gas
| Others |
| A | Alveolization
| Others |
| A | Amendment of Application
| Others |
| A | American
| Others |
| A | American Bank Note Company
| Others |
| A | Ampere
| Measurement Unit, Electricity |
| A | Anal
| Others |
| A | Analog
| Others |
| A | Analog signal
| Others |
| A | Analysis
| Others |
| A | Anaphylaxis
| Others |
| A | Ancyclostoma
| Others |
| A | Andrei
| Others |
| A | Anglo American Cataloguing Rule
| Others |
| A | Angstrom
| Others |
| A | Animal
| Others |
| A | Animals
| Others |
| A | Anion
| Others |
| A | Ankle Jerk/Reflex
| Others |
| A | Ann
| Others |
| A | Annealing
| Others |
| A | Annihilation
| Others |
| A | Annoying
| Others |
| A | Anode
| Others |
| A | anoxia/reoxygenation
| Others |
| A | Ant
| Others |
| A | Anteater
| Others |
| A | Anterior
| Others |
| A | antinuclear antibody (ANA is more commonly used)
| Others |
| A | Ape
| Others |
| A | Aperture
| Others |
| A | apical/radial
| Others |
| A | Apple
| Others |
| A | Appropriate
| Others |
| A | Approved
| Others |
| A | Apron
| Others |
| A | Aqua
| Others |
| A | Aqueous
| Others |
| A | Arbitration
| Others |
| A | Archived
| Others |
| A | Archives
| Others |
| A | Area
| Others |
| A | Art
| Others |
| A | Arte
| Others |
| A | Artemis
| Others |
| A | Arterial
| Others |
| A | Arteriolar
| Others |
| A | Artery
| Others |
| A | As
| Others |
| A | Asbestos
| Others |
| A | Ascaris
| Others |
| A | Asexual
| Others |
| A | Asparagine
| Others |
| A | Assist
| Others |
| A | Atom
| Others |
| A | Atomic
| Others |
| A | Atrial
| Others |
| A | Atrium
| Others |
| A | Atropine
| Others |
| A | augmenting reducing
| Others |
| A | Auricular
| Others |
| A | auris (ear)
| Others |
| A | Australian
| Others |
| A | Autos
| Others |
| A | Ava
| Others |
| A | Avance
| Others |
| A | Avianca Airlines
| Others |
| A | Awesome
| Others |
| A | Axis
| Others |
| a | before (from Latin ante)
| Others |
| A | Blood Type
| Others |
| a | chemical activity
| Others |
| A | for Aircraft
| Others |
| A | form A (normally open) contacts
| Others |
| A | Helmholtz Energy
| Others |
| A | mass number
| Others |
| A | radioactivity
| Others |
| A | The Arts
| Others |
| A. | Atlantic Reporter
| Others |