1. 航空；飞机制造业
Aviation is the operation and production of aircraft.

1. travel via aircraft

e.g. air travel involves too much waiting in airports
if you've time to spare go by air

Synonym: air travelair

2. the art of operating aircraft

Synonym: airmanship

3. the operation of aircraft to provide transportation

4. the aggregation of a country's military aircraft

Synonym: air power