China 
Africa 
- Accident-proneness
- Accidents
- Acclimatization
- Accommodation
- Accommodation space
- Accountability
- Accounting rate of return
- Accreditation
- Accredited
- Accretion
- Accretion disks
- Accretionary wedge
- Accumulation
- Accumulation point
- Accumulator
- Accuracy and precision
- Acellular
- Acenaphthene
- Acenaphthylene
- Acene
- Acenocoumarol
- Acentric factor
- Acetabular
- Acetabular labrum
- Acetal
- Acetaldehyde
- Acetaldehyde dehydrogenase
- Acetamide
- Acetanilide
- Acetate
- Acetate kinase
- Acetazolamide
- Acetic acid
- Acetic acid bacteria
- Acetic anhydride
- Acetoacetate
- Acetoacetic acid
- Acetobacter aceti
- Acetochlor
- Acetogen
- Acetogenesis
- Acetoin
- Acetolactate synthase
- Acetone
- Acetone cyanohydrin
- Acetonitrile
- Acetophenone
- Acetosyringone
- Acetyl
- Acetyl chloride
- Acetyl group
- Acetyl iodide
- Acetyl-CoA synthetase
- Acetylacetone
- Acetylation
- Acetylcholine
- Acetylcholine receptor
- Acetylcholinesterase
- Acetylcholinesterase inhibitors
- Acetylene
- Acetylenic
- Acetylide
- Acetyltransferase
- Achalasia
- Achilles tendon
- Achilles tendon rupture
- Achiral
- Achromatic lenses
- Achromatopsia
- Aciclovir
- Acicular
- Acicular ferrite
- Acid
- Acid attack
- Acid catalysis
- Acid catalysts
- Acid dissociation constant
- Acid dyes
- Acid fuchsin
- Acid gas
- Acid hydrolysis
- Acid neutralizing capacity
- Acid phosphatase
- Acid rain
- Acid salts
- Acid strength
- Acid sulfate soils
- Acid value
- Acid wash
- Acid-base extraction
- Acid-base homeostasis
- Acid-base reaction
- Acid-base titration
- Acid-citrate-dextrose
- Acid-fast
- Acidification
- Acidifiers
- Acidithiobacillus ferrooxidans
- Acidithiobacillus thiooxidans
- Acidity
- Acidity regulator
- Acidogenesis
- Acidogenic
- Acidophiles
- Acidosis
- Acidulants
- Acinar
- Acinar cells
- Acinetobacter baumannii
- Acini
- Acipimox
- Ackley function
- Acknowledgement
- Acne
- Acoustic attenuation
- Acoustic camera
- Acoustic droplet vaporization
- Acoustic ecology
- Acoustic emission
- Acoustic holography
- Acoustic impedance
- Acoustic liners
- Acoustic metamaterial
- Acoustic metamaterials
- Acoustic microscopy
- Acoustic models
- Acoustic plaster
- Acoustic radiation
- Acoustic radiation force
- Acoustic radiation pressure
- Acoustic reflex
- Acoustic resonance
- Acoustic shock
- Acoustic signature
- Acoustic streaming
- Acoustic transmission
- Acoustic wave equation
- Acoustic waveguide
- Acoustic waves
- Acoustical engineering
- Acoustics
- Acousto-optic modulator
- Acousto-optics
- Acoustoelastic effect
- Acquired
- Acquired brain injury
- Acre
- Acre-foot
- Acridine
- Acridine orange