also air-line, 1813, "beeline, straight line between two points on the earth's surface" (as through the air, rather than over terrain; from 1853 and in later 19c. especially in reference to railways that ran directly between big cities in the U.S. instead of meandering from town to town in search of stock subscriptions as early railways typically did), from air (n.1) + line (n.). Meaning "public aircraft transportation company" is from 1914.
1. The airline had losses of $35m and was bailed out by Qantas.
2. The drop in travel is bad news for the airline industry.
3. The £85m programme will involve an extensive rebranding of the airline.
4. The airline had been screening baggage on X-ray machines.
5. This year the airline will be hard-pressed to make a profit.