空

Engineering

superficial velocity; superficial flow velocity

geospatial

airplane mode (setting on an electronic device); flight mode

Mathematics

linear space

Mathematics

Banach space

elevated railway; overhead railway

Common noun

canoe, etc. in very clear water (illusion of flying)

Pronoun

Flying Canoe (Canadian folk-tale)

aneroid barometer

aerial cableway; ropeway

pedestrian zone; pedestrian space

vactrain; vacuum tube train

Law

specially designated vacant house; vacant house that has been declared dangerous or dilapidated by the local authority and may be subject to higher taxes, fines or demolition

Linguistics

false friend

airborne wind power generation; kite power generation

white-spotted pufferfish (Torquigener albomaculosus)

flight ticket; air ticket

aviation business; air transport service

Military

hypersonic glide vehicle; hypersonic glide weapon

Military

unsinkable aircraft carrier

aerial ropeway

brake reaction distance; brake lag distance

brake lag

air brake

airport terminal