Plain English Meaning
The airport you take off from. It is where your flight starts.
Full Definition
The airport from which a flight originates — the location where the aircraft takes off at the beginning of a planned flight.
Context Anchor
In energy management and emergency planning, pilots may refer to the departure airport when deciding whether returning to the takeoff airport is still possible.
Derivation
From the Latin 'departire,' meaning 'to divide' or 'to go away from.' The departure airport is simply the airport you are going away from at the start of the flight.
Why Pilots Care
It sets the reference point for takeoff performance, fuel planning, and weather requirements before any enroute or calculations begin.