WordReference Random House Unabridged Dictionary of American English © 2019
traveling a direct route:Some railroads advertise air-line routes between stations.
- 1805–15, American.
air•line (âr′līn′),USA pronunciation n.
- a system furnishing air transport, usually scheduled, between specified points.
- the airplanes, airports, etc., of such a system.
- Often, airlines. a company that owns or operates such a system.
- a direct line;
- Mechanical Engineeringan airhose used to pipe air to a deep-sea diver, pneumatic drill, etc.
- of or on an airline.
- air1 + line1 1910–15