China 
Africa 
- Absolute zero
- Absorbed dose
- Absorbency
- Absorption
- Absorption cross section
- Absorption rate constant
- Absorption spectroscopy
- Absorptive state
- Absorptivity
- Abstinence
- Abstinence-only sex education
- Abulia
- Abusive supervision
- Abutment
- Abzymes
- Acacetin
- Acacia
- Academic detailing
- Academic medicine
- Acalabrutinib
- Acalculous cholecystitis
- Acalypha indica
- Acam2000
- Acamprosate
- Acanthamoeba
- Acanthamoeba castellanii
- Acanthamoeba infection
- Acanthamoeba keratitis
- Acanthamoeba polyphaga
- Acanthocyte
- Acanthocytosis
- Acantholysis
- Acanthoma
- Acanthosis
- Acanthosis nigricans
- Acaricides
- Accelerated aging
- Accelerated approval
- Accelerated idioventricular rhythm
- Acceleration
- Acceleromyograph
- Acceptable daily intake
- Acceptance
- Acceptance and commitment therapy
- Acceptance sampling
- Accessible housing
- Accessible surface area
- Accession number
- Accessory bone
- Accessory breast
- Accessory cell
- Accessory hemiazygos vein
- Accessory lacrimal glands
- Accessory muscle
- Accessory navicular bone
- Accessory nerve
- Accessory nucleus
- Accessory obturator nerve
- Accessory pancreatic duct
- Accessory pathway
- Accessory saphenous vein
- Accessory sex glands
- Accessory spleens
- Accident prevention
- Accident proneness
- Accidental death
- Accidental hypothermia
- Accidental poisoning
- Acclimation
- Acclimatisation
- Acclimatization
- Accommodation reflex
- Accommodative
- Accommodative convergence
- Accountability
- Accreditation
- Acecainide
- Aceclofenac
- Acedia
- Acellular dermis
- Acemannan
- Acemetacin
- Acenocoumarol
- Acentric fragment
- Acephate
- Acer negundo
- Acer saccharum
- Acerola
- Aceruloplasminemia
- Acesulfame
- Acesulfame potassium
- Acetabular
- Acetabular fossa
- Acetabular fracture
- Acetabular labrum
- Acetabular notch
- Acetal
- Acetaldehyde
- Acetaldehyde dehydrogenase
- Acetamide
- Acetaminophen
- Acetamiprid
- Acetate
- Acetate ester
- Acetate kinase
- Acetazolamide
- Acetic acid
- Acetic acid bacteria
- Acetoacetic acid
- Acetobacter
- Acetogen
- Acetogenin
- Acetohexamide
- Acetohydroxamic acid
- Acetone
- Acetonide
- Acetonitrile
- Acetophenone
- Acetosyringone
- Acetyl chloride
- Acetyl coa carboxylase
- Acetyl coa synthetase
- Acetyl coenzyme A carboxylase
- Acetyl hexapeptide-3
- Acetyl-CoA carboxylase
- Acetyl-CoA hydrolase
- Acetyl-CoA synthetase
- Acetylation
- Acetylcarnitine
- Acetylcholine
- Acetylcholine receptors
- Acetylcholinesterase
- Acetylcholinesterase inhibitors
- Acetylcysteine
- Acetyldigoxin
- Acetylene
- Acetylenic
- Acetylesterase
- Acetyllysine
- Acetylmethadol
- Acetylpropionyl
- Acetylsalicylic acid
- Acetylserotonin O-methyltransferase
- Acetyltransferase
- Acetyltransferases
- Achalasia
- Achillea millefolium
- Achilles reflex
- Achilles tendinitis
- Achilles tendon