China 
Africa 
- Angle of refraction
- Angle of the mandible
- Angle-closure glaucoma
- Angst
- Angular Spectrum Method
- Angular artery
- Angular cheilitis
- Angular gyrus
- Angular vein
- Anhedonia
- Anhidrosis
- Anhydrous ammonia
- Anidulafungin
- Anifrolumab
- Anilide
- Aniline
- Anilingus
- Animal
- Animal Efficacy Rule
- Animal allergy
- Animal assisted therapy
- Animal bite
- Animal byproducts
- Animal cell
- Animal disease model
- Animal fat
- Animal models
- Animal models of Parkinson's disease
- Animal models of depression
- Animal models of epilepsy
- Animal models of stroke
- Animal physiology
- Animal products
- Animal studies
- Animal tissue
- Animal trypanosomiasis
- Animal virus
- Animal viruses
- Animalia
- Anion channel
- Anion exchange
- Anion exchange chromatography
- Anion gap
- Anion-exchange chromatography
- Anionic surfactant
- Anions
- Aniracetam
- Aniridia
- Anisakiasis
- Anisakidae
- Anisakis
- Anisakis simplex
- Anise
- Anise oil
- Aniseikonia
- Anisic acid
- Anismus
- Anisochromia
- Anisocoria
- Anisocytosis
- Anisodamine
- Anisometropia
- Anisomycin
- Anisopoikilocytosis
- Ankle
- Ankle arthrodesis
- Ankle brace
- Ankle brachial index
- Ankle brachial pressure index
- Ankle foot orthosis
- Ankle joint
- Ankle pressure
- Ankle replacement
- Ankle sprain
- Ankle-brachial index
- Ankyloblepharon
- Ankyloglossia
- Ankylosing spondylitis
- Ankylosis
- Ankyrin
- Anma
- Ann Arbor staging
- Anna Karenina principle
- Annatto
- Annexin
- Annexin A1
- Annexin A2
- Annexin A5
- Annona muricata
- Annonaceae
- Annovera
- Annoyance
- Annular ligament
- Annular pancreas
- Annular pustular psoriasis
- Annuloaortic ectasia
- Annuloplasty
- Annuloplasty ring
- Annulus fibrosus
- Anodyne
- Anogenital distance
- Anoikis
- Anomalies
- Anomalous diffusion
- Anomalous left coronary artery from the pulmonary artery
- Anomalous pulmonary venous connection
- Anomaly scan
- Anomeric
- Anomia
- Anomic aphasia
- Anomie
- Anonaine
- Anonychia
- Anopheles
- Anopheles culicifacies
- Anopheles gambiae
- Anopheles sinensis
- Anophthalmia
- Anopia
- Anopsia
- Anorchia
- Anorectal abscess
- Anorectal anomalies
- Anorectal canal
- Anorectal manometry
- Anorectic
- Anorexia
- Anorexia athletica
- Anorexia nervosa
- Anorgasmia
- Anoscopy
- Anosmia
- Anosmin-1
- Anosodiaphoria
- Anosognosia
- Anotia
- Anovulation
- Anovulatory cycle
- Anoxia
- Anrep effect
- Ansa cervicalis
- Ansa lenticularis
- Ansamycin
- Ant venom
- Antacids
- Antagomir
- Antagonism
- Antagonist muscle
- Antalarmin
- Antalgic gait