- asphalting
- asphyxiating gas
- aspirate
- aspiration
- aspiration pipe
- aspiration pump
- aspiring pump
- assemble
- assembler operator
- assembly economics
- assembly line
- assembly routine
- assertion
- assessed income
- asset
- assignable cause
- assignment
- assignment statement
- assistant engine
- assisting locomotive
- associated
- associative
- associative law
- associative register
- associative search
- associator
- assured discharge
- astable
- astatic
- astatic galvanometer
- astatization
- astragal
- astral oil
- astronomic point
- astronomical time
- asymmetric fold
- asymptotic line
- asymptotical stability
- asynchronous communication
- asynchronous device
- asynchronous transmission
- at last
- at most
- at times
- athletic field
- athwart
- atlas
- atmospheric drag
- atmospheric pressure
- atmospheric rock
- atmospheric waveguide
- atmospherical pressure
- atomic
- atomic battery
- atomic boiler
- atomic clock
- atomic energy
- atomic number
- atomic weight
- atomical
- atomization
- atomize
- atomizer
- atop
- atopic
- attached
- aqueous soil
- aquiclude
- arable
- aragonite
- arbitrary
- arbor hole
- arc converter
- arc discharge
- arc welding
- arcade game
- arch bend
- arch center
- arch crossover
- arch keystone
- arch rib
- arch roof
- arch-flat
- archaeohydrology
- archigaster
- architect
- architect scale
- architectural
- architrave
- archived flag
- archiving destination
- archwise
- arcing
- arcing lamp
- are gap
- area density
- area graph
- area triangulation
- arena
- areometer