- A-index
- abbreviated install
- ablation material
- ablative cooling
- abnormal reaction
- abort
- abrupt junction
- absolute order
- absolute reference
- absolute stability
- absolute system
- absolute zero
- absorbing clamp
- absorbing screen
- absorption cell
- absorption wavemeter
- absorptive modulator
- acceleration asensor
- acceptance angle
- acceptance test
- accepted interference
- access code
- access environment
- access exchange
- access port
- access procedure
- access system
- accident statistics
- account
- accounting rate
- accumulation cycle
- abbreviated addressing
- aberration
- ablation product
- abscissa
- absolute coding
- absolute constant
- absolute priority
- absorption length
- absorptive attenuator
- absorptivity
- absolute magnitude
- absolute symbol
- absolute time
- absolute vector
- absorption spectrometry
- AC coupler
- AC meter
- accelerated test
- acceptable distortion
- access capability
- access channel
- access circuit
- access control
- access point
- accompanying sound
- accounting device
- acceptance line
- access concentrator
- access memory
- access mode
- access name
- access number
- access priority
- access speed
- access type
- accessing model
- account payable
- account receivable
- accountability information
- accounting records
- accretion
- accrued liabilities
- accumulation factor
- accumulator
- acknowledged mail
- acknowledgment bit
- acorn tube
- acoustic delay
- acoustic resonator
- acoustic storage
- acoustical branch
- acoustical component
- acquired session
- acquisition station
- action limit
- action message
- action space
- action statement
- active channel
- active color
- active computer
- active dipole
- active filtering
- active integrator
- active load
- active mode
- active network
- active processor
- active reactance