窪む

Etymology 1
Verb derived from noun /  + verbalizing suffix.

Verb

 * 1) to become hollow, cave in, sink in

Usage notes
The transitive form is /. Consequently, the potential form is the same as the passive form,, instead of as shown incorrectly in the table above.

The spelling is used more often for, because the alternative spelling  can also be read as.

Etymology 2
Appears in texts from the.

Ultimate derivation unclear. May be derived from adjective, which was used ironically to mean the opposite of its usual positive connotations.

Verb

 * 1)  to deform, to become deformed
 * 2)  to become cracked