noun
boarding
BOR-ding/ˈbɔːrdɪŋ/
The act of getting onto a vehicle or vessel.
Boarding proceeds as passengers step through the aircraft doorway.

Etymology
From the ship's side came the action of coming alongside a vessel, then getting onto it. Boarding names that action, which later extended from ships to railway cars, aircraft, and other vehicles.
In context
This is where boarding a craft that flies you across the world
in the first few minutes after boarding a flight.
More examples
- Please have your ticket ready before boarding.
- Ferry boarding begins at the lower ramp.
- The bus company provides assistance during boarding.
Similar words
- embarkation
- A more formal term, especially for ships or aircraft.