When an aircraft or spacecraft touches down it reaches the ground when landing.
Example of use:
Good afternoon ladies and gentlemen. Your flight will touch down in 10 minutes. Please fasten your seatbelts.
touchdown (noun) is the moment an aircraft or spacecraft makes contact with the ground when it lands.
Example of use:
Touchdown will be at seventeen hundred hours.
In rugby, to touch down is to score by putting the rugby ball on the ground behind the other team’s goal line.
Example of use:
The rugby player ran past his opponents and touched down in the left corner.
In rugby, a touchdown (noun) is the act of placing the ball on the ground.
Example of use:
He scored four touchdowns.
In American football, a touchdown (noun) is the act of receiving or having possession of the ball across the opponents’ goal line.
infinitive – touch down
present simple – touch down and touches down
-ing form – touching down
past simple – touched down
past participle – touched down
Image by David Kusserow