| A&O | alert and oriented |
| A&O×3 | awake (or alert) and oriented to person, place, and time |
| A&O×4 | awake (or alert) and oriented to person, place, time, and situation |
| A&P | active and present; anterior and posterior; assessment and plans; auscultation and percussion |
| A&W | alive and well |
| A1c | hemoglobin A1c |
| AA | aplastic anemia; Alcoholics Anonymous |
| AAA | abdominal aortic aneurysm |
| AAO | awake, alert, and oriented |
| AAO×3 | awake and orientated to time, place, and person |
| ABC | absolute band counts; absolute basophil count; apnea, bradycardia, and cytology; aspiration, biopsy, and cytology; artificial beta cells |
| Abd | abdomen |
| ABG | arterial blood gases |
| ABO | blood group system (A, AB, B, and O) |
| ABP | arterial blood pressure |
| ABW | actual body weight |
| ABx | antibiotics |
| AC | before meals (ante cibos) |
| ACE | angiotensin-converting enzyme |
| ACE-I | angiotensin-converting enzyme inhibitor |
| ACLS | advanced cardiac life support |
| ACS | acute coronary syndromes |
| ACTH | adrenocorticotropic hormone |
| AD | Alzheimer disease; right ear (auris dextra) |
| ADA | American Diabetes Association; adenosine deaminase |
| ADE | adverse drug effect (or event) |
| ADH | antidiuretic hormone |
| ADHD | attention-deficit hyperactivity disorder |
| ADL | activities of daily living |
| ADR | adverse drug reaction |
| AF | atrial fibrillation |
| AFB | acid-fast bacillus; aortofemoral bypass; aspirated foreign body |
| AFEB | afebrile |
| AI | aortic insufficiency |
| AIDS | acquired immune deficiency syndrome |
| AKA | above-knee amputation; alcoholic ketoacidosis; all known allergies; also known as |
| AKI | acute kidney injury |
| ALFT | abnormal liver function test |
| ALL | acute lymphoblastic leukemia; acute lymphocytic leukemia |
| ALP | alkaline phosphatase |
| ALS | amyotrophic lateral sclerosis |
| ALT | alanine transaminase (SGPT); alanine aminotransferase |
| AMA | against medical advice; American Medical Association; antimitochondrial antibody |
| AMI | acute myocardial infarction |
| AML | acute myelogenous leukemia |
| Amp | ampule |
| ANA | antinuclear antibody |
| ANC | absolute neutrophil count |
| ANLL | acute nonlymphocytic leukemia |
| AODM | adult-onset diabetes mellitus |
| AOM | acute otitis media |
| AP | anteroposterior |
| APAP | acetaminophen (acetyl-p-aminophenol) |
| aPTT | activated partial thromboplastin time |
| ARB | angiotensin receptor blocker |
| ARC | AIDS-related complex |
| ARD | acute respiratory disease; adult respiratory disease; antibiotic removal device; aphakic retinal detachment |
| ARDS | adult respiratory distress syndrome |
| ARF | acute renal failure; acute respiratory failure; acute rheumatic fever |
| AROM | active range of motion |
| AS | left ear (auris sinistra) |
| ASA | aspirin (acetylsalicylic acid) |
| ASCVD | arteriosclerotic cardiovascular disease |
| ASD | atrial septal defect |
| ASH | asymmetric septal hypertrophy |
| ASHD | arteriosclerotic heart disease |
| AST | aspartate transaminase (SGOT); aspartate aminotransferase |
| ATG | antithymocyte globulin |
| ATN | acute tubular necrosis |
| AU | each ear (auris uterque) |
| AV | arteriovenous; atrioventricular; auditory visual |
| AVR | aortic valve replacement |
| BBB | bundle branch block; blood−brain barrier |
| BC | blood culture |
| BCOP | Board Certified Oncology Pharmacist |
| BCP | birth control pill |
| BCPP | Board Certified Psychiatric Pharmacist |
| BCPS | Board Certified Pharmacotherapy Specialist |
| BE | barium enema |
| BG | blood glucose |
| bid | twice daily (bis in die) |
| BKA | below-knee amputation |
| BM | bone marrow; bowel movement; an isoenzyme of creatine phosphokinase |
| BMC | bone marrow cells |
| BMD | bone mineral density |
| BMI | body mass index |
| BMP | basic metabolic panel |
| BMR | basal metabolic rate |
| BMT | bone marrow transplantation |
| BP | blood pressure |
| BPD | bronchopulmonary ... |