- APRV
- AQP1
- AQP4
- ARAF
- ARC
- ARDS
- AREDS
- ARF6
- ARID1A
- ARID1B
- ARID2
- ART
- ARVC
- ARVD
- AS03
- AS04
- ASA physical status classification system
- ASCUS
- ASD
- ASH1L
- ASIC1
- ASIC2
- ASIC3
- ASIC4
- ASMT
- ASO
- ASPSCR1
- AST ALT ratio
- AT-076
- AT-121
- AT-hook
- ATAC-seq
- ATE
- ATF2
- ATF3
- ATF4
- ATF5
- ATF6
- ATG8
- ATLS
- ATM
- ATMP
- ATOH1
- ATP hydrolysis
- ATP synthase
- ATP-binding cassette family
- ATP-binding cassette transporter
- ATP-binding motifs
- ATP7B
- ATP8B1
- ATPase
- ATPase assay
- ATX-II
- ATXN1
- AU-rich elements
- AUDIT
- AV
- AV nodal reentrant tachycardia
- AVP gene
- AVPU
- AZT
- Aadhaar
- Aagenaes syndrome
- Ab-fubinaca
- Abacavir
- Abarelix
- Abasia
- Abatacept
- Abbreviated Injury Scale
- Abbreviated mental test score
- Abcd4
- Abciximab
- Abdala
- Abdomen
- Abdominal angina
- Abdominal aortic
- Abdominal aortic aneurysm
- Abdominal aortic aneurysm repair
- Abdominal cavity
- Abdominal compartment syndrome
- Abdominal discomfort
- Abdominal distension
- Abdominal examination
- Abdominal fascia
- Abdominal fat
- Abdominal guarding
- Abdominal hysterectomy
- Abdominal mass
- Abdominal migraine
- Abdominal muscles
- Abdominal obesity
- Abdominal pain
- Abdominal pregnancy
- Abdominal radiography
- Abdominal reflex
- Abdominal surgery
- Abdominal swelling
- Abdominal thrusts
- Abdominal trauma
- Abdominal ultrasonography
- Abdominal wall
- Abdominal wall defects
- Abdominal x-ray
- Abdominoperineal resection
- Abdominoplasty
- Abducens nerve
- Abducens nucleus
- Abductor digiti minimi
- Abductor hallucis
- Abductor hallucis muscle
- Abductor pollicis brevis
- Abductor pollicis brevis muscle
- Abductor pollicis longus
- Abelson murine leukemia virus
- Abemaciclib
- Abequose
- Aberrant crypt foci
- Aberrant subclavian artery
- Aberrations of the eye
- Abetalipoproteinemia
- Abietane
- Abietic acid
- Ability
- Abiogenesis
- Abiotic stress
- Abiotrophia
- Abiraterone
- Abiraterone acetate
- Ablation
- Abnormal posture
- Abnormal posturing
- Abnormal thinking
- Abnormality
- Abomasal
- Abortifacients
- Abortion
- Abortion clinics
- Above knee amputation
- Abrasion
- Abreaction
- Abrin
- Abscesses
- Abscisic acid
- Abscopal effect
- Absence
- Absence seizures
- Absent-mindedness
- Absolute configuration
- Absolute risk
- Absolute threshold