- atto
- attoelectronic emission
- attract
- attraction
- attractive
- attractive force
- attractive power
- attribute
- attribute character
- attribute domain
- attribute label
- attribute sampling
- attribution
- attrite
- attrition
- attrition mill
- attrition test
- auction
- audibility meter
- audibility threshold
- audible spectrum
- audible test
- audio amplifier
- audio engineering
- audio generator
- audio head
- audio level
- audio modulation
- audio operator
- audio output
- audio range
- audio reproduction
- audio signal
- audio tape
- audio transmission
- audiofrequency spectrometer
- audiography
- audiometer
- audiosignal
- audiovisual system
- audiovisual zoom
- audit log
- audit total
- audition
- auditor
- auditorium
- auger
- augment
- augmention
- aunt
- aural
- aural detector
- aural harmonic
- aural perception
- aural signal
- aureole
- aurora
- aurora-polaris
- aurum
- authentic document
- authenticate
- authentication code
- authentication token
- author
- authoring language
- authoring system
- authority
- authorization
- authorize
- authorized bank
- authorized receiver
- authorized user
- auto
- auto decompressor
- auto jumb
- auto mechanics
- auto mode
- auto program
- auto-action
- auto-exchange
- auto-generating
- auto-induction
- auto-login
- auto-manual
- auto-oscillation
- autochthonous
- autochthonous mantle
- autoclave digester
- autoclaving
- autocoder
- autocollimator
- autocorrelation
- autocorrelation analyser
- autocorrelation vocoder
- autocrane
- autodyne circuit
- autofining
- autofrettage
- autogenous
- autogenous welding