godan verb (-ru), intransitive verb
Rare intransitive verb describing a surface becoming dented, sunken, or depressed. Often replaced by the more common 窪む (くぼむ) in modern usage.
See also: 窪む
古いソファの座面が窪まってしまった。
The seat of the old sofa has become sunken.
The ground caved in from the rain.