1. a scoring play in American football worth six points, achieved by advancing the ball into the opponent’s end zone
2. the moment when an aircraft or spacecraft makes contact with the ground during landing

1. to score a touchdown in football
2. to land on the ground (of an aircraft or spacecraft)

Examples

• The quarterback threw a pass for a touchdown in the final seconds.
• Our team scored three touchdowns in the first half.
• The airplane’s touchdown was smooth despite the windy conditions.
• Mission control confirmed the spacecraft’s successful touchdown on Mars.
• The running back managed to touchdown despite heavy defense.
• The pilot announced we would touchdown in ten minutes.
• That was the winning touchdown of the championship game.