| AAOHN | American Association of Occupational Health Nurses |
|---|---|
| AAOM | American Academy of Oral Medicine |
| AAOO | American Academy of Ophthalmology and Otolaryngology |
| AAOP | American Academy of Oral Pathology |
| AAOPP | American Association of Osteopathic Postgraduate Physicians |
| AAOS | American Academy of Orthopedic Surgeons |
| AAP | air at atmospheric pressure; American Academy of Pediatrics; American Academy of Pedodontics; American Academy of Periodontology; American Academy of Psychoanalysts; American Academy of Psychotherapists; American Association of Pathologists; Association for the Advancement of Psychoanalysis; Association for the Advancement of Psychotherapy; Association of Academic Physiatrists; Association of American Physicians |
| AAPA | American Academy of Physician Assistants; American Association of Pathologist Assistants |
| AAPB | American Association of Pathologists and Bacteriologists |
| AAPC | antibiotic-associated pseudomembranous colitis |