- agrobiology
- agrochemistry
- agronomic pedology
- air chipper
- air conveyor
- air engine
- air heater
- air impermeability
- air injector
- air level
- air manifold
- air nozzle
- air outlet
- air passage
- air pump
- air receiver
- air soring
- air test
- air traffic
- air turbine
- air vacuum
- aircraft
- agricultural atlas
- agricultural engineer
- agroclimatology
- aid
- aiming point
- air box
- air chamber
- air clutch
- air cylinder
- air drilling
- air inlet
- air line
- air reservoir
- air seasoning
- air space
- air tool
- air-dry
- air-hardened
- aircraft carrier
- aisle
- aircraft steel
- aircushion craft
- airfoil
- airship
- airside face
- airworthiness
- alarm
- albaloy
- alignment test
- alimentation area
- alkali reaction
- alkalimetry
- alkaline cleaner
- alkalization
- all-around
- alligator shears
- allocation
- allogenic river
- allotment
- agricultural investigation
- agrimotor
- air booster
- air brake
- air case
- air circularity
- air cleaner
- air cock
- air collector
- air gage
- air hoist
- air pocket
- air seal
- air separator
- air starter
- air supply
- airslide
- alclad
- alcohol level
- aldural
- alidade
- align
- aligning mark
- alignment
- alignment tapping
- alive
- alkalescence
- alkalimeter
- all-rounder
- all-welded
- allied rock
- alligator squeezer
- allowable
- allowance
- allowance clearance
- alloy
- alloy constituent
- alloying constituent
- alluvial deposit