China 
Africa 
- Aloe emodin
- Aloe-emodin
- Alopecia
- Alopecia areata
- Alpha
- Alpha 1-antitrypsin
- Alpha carbon
- Alpha case
- Alpha cells
- Alpha channel
- Alpha cleavage
- Alpha decay
- Alpha defensin
- Alpha diversity
- Alpha helices
- Alpha helix
- Alpha motor neuron
- Alpha particles
- Alpha quartz
- Alpha shape
- Alpha waves
- Alpha-1 antitrypsin
- Alpha-1 antitrypsin deficiency
- Alpha-actinin
- Alpha-amylase
- Alpha-fetoprotein
- Alpha-olefin sulfonate
- Alpha-synuclein
- Alpha-tocopherol
- AlphaGo
- AlphaGo Zero
- Alphabet
- Alphafold
- Alphaproteobacteria
- Alpide belt
- Alpine Fault
- Alq3
- Altaite
- Alteration
- Altered
- Altered level of consciousness
- Alternating group
- Alternating series
- Alternating series test
- Alternative cancer treatments
- Alternative frequency
- Alternative fuel
- Alternative fuel vehicles
- Alternative hypothesis
- Alternative oxidase
- Alternative splicing
- Alternative technology
- Alternatives assessment
- Alternators
- Alteromonadales
- Altimeter
- Altitude
- Altitude sickness
- Altitude training
- Alu elements
- Alum
- Alumel
- Alumina
- Aluminate
- Aluminides
- Aluminium
- Aluminium alloys
- Aluminium battery
- Aluminium bronze
- Aluminium carbide
- Aluminium chlorohydrate
- Aluminium compounds
- Aluminium foil
- Aluminium gallium arsenide
- Aluminium gallium nitride
- Aluminium hydride
- Aluminium hydroxide
- Aluminium isopropoxide
- Aluminium nitrate
- Aluminium nitride
- Aluminium oxide
- Aluminium oxide hydroxide
- Aluminium oxynitride
- Aluminium phosphate
- Aluminium phosphide
- Aluminium recycling
- Aluminium silicate
- Aluminium smelting
- Aluminium sulfate
- Aluminium toxicity
- Aluminium-air battery
- Aluminium-copper alloys
- Aluminium-lithium alloy
- Aluminium-lithium alloys
- Aluminium-magnesium alloys
- Aluminium-silicon alloys
- Aluminized steel
- Aluminosilicate
- Aluminum can
- Aluminum electrolytic capacitor
- Aluminum foil
- Aluminum powder
- Aluminum wire
- Alunite
- Alveolar
- Alveolar macrophages
- Alveolar nerve
- Alveolar pressure
- Alveolar process
- Alveolar ridge
- Alveoli
- Alzheimer's disease
- Amacrine cells
- Amalgam
- Amantadine
- Amaranth
- Amateur radio
- Amatol
- Amazon Alexa
- Amazon EC2
- Amazon Echo
- Amazon Elastic Compute Cloud
- Amazon Machine Image
- Amazon Mechanical Turk
- Amazon Relational Database Service
- Amber
- Ambidextrous
- Ambient backscatter
- Ambient light sensors
- Ambient noise level
- Ambient occlusion
- Ambient pressure
- Ambiguity
- Ambiguity aversion
- Ambiguity function
- Ambiguity resolution
- Ambipolar diffusion
- Ambisonics
- Amblygonite
- Amblyopia
- Ambulances
- Ambulatory blood pressure
- Ambulatory blood pressure monitoring
- Amdahl's Law
- Ameloblasts
- Amelogenin
- Amendments
- American Ceramic Society
- American Iron and Steel Institute
- Americium