- acoustic coupler
- acoustic dispersion
- acoustic enclosure
- acoustic microscope
- acoustic pressure
- acoustic quantities
- acoustical holography
- acousto-electric
- acoustooptical cell
- actinodielectric
- actinon
- actinotherapy
- action variable
- active
- active circuit
- active component
- active current
- active material
- active network
- active surface
- active use
- active voltage
- activity
- activity ratio
- actual cycle
- actual differential
- actual displacement
- actuator drive
- acyclic machine
- acknowledgment
- aclinic
- acoustic clarifier
- acoustic compliance
- acoustic levitation
- acoustic positioning
- acoustic refraction
- acoustic sounding
- acoustic stiffness
- acoustical image
- actinodielectricity
- actual position
- actual value
- ad
- adapted
- adapter transformer
- adaptive control
- adaptor
- additional air
- additional ventilation
- additive
- adiabatic absorption
- adiabatic compression
- adiabatic cooling
- adiabatic demagnetization
- adiabatic envelope
- adiabatic exponent
- adiabatic vaporization
- adjustable clearance
- adjustable diffuser
- adjustable transformer
- adjustment control
- adjustment tolerance
- adapter
- additional broadening
- adhesional work
- adiabatic approximation
- adiabatic change
- adiabatic desorption
- adiabatic efficiency
- adiabatic evaporation
- adiabatic expansion
- adiabatic flow
- adiabatic horsepower
- adiabatic saturation
- adiabatic throttling
- adiathermanous
- adjacent
- adjustable capacitor
- adjustable damper
- adjustable louvre
- adjustment
- admittance bridge
- admittance diagram
- adsorbability
- adsorbate
- adsorbed
- adsorbed charge
- adsorbed substance
- adsorbent bed
- adsorbent medium
- adsorption bed
- adsorption dehumidifier
- adsorption efficiency
- advanced battery
- advanced opening
- advective
- aeolian fan
- aerate
- aerated building
- aeration