| ARA | Academy of Rehabilitative Audiometry; acetylene reduction activity; American Rheumatism Association;... |
|---|---|
| ARIA | acetylcholine receptor-inducing activity; automated radioimmunoassay |
| ATA | alimentary toxic aleukia; American Thyroid Association; aminotriazole; antithymic activity; antithyr... |
| AVA | activity vector analysis; antiviral antibody; aortic valve area; aortic valve atresia; arteriovenous... |
| aw | airway; water activity |