To go down or set, often used in reference to the sun or other celestial bodies. verb
The sun will untergehen at 6 PM today.
As the moon began to untergehen, the stars became more visible.
To perish, be destroyed, or cease to exist. verb
The ancient civilization began to untergehen after the invasion.
Without proper care, the neglected garden started to untergehen.
To sink or submerge, often used in reference to ships or objects in water. verb
The ship hit an iceberg and began to untergehen rapidly.
During the storm, several small boats were at risk of untergehen.