This is the 17210th most frequent Polish word.
zaginięciem
"Zaginięciem" means "disappearance" in English.
The word "zaginięcia" here is used in the instrumental case, indicating the reason or cause being addressed.
Policja zajęła się sprawą jego zaginięcia.
The police took up the case of his disappearance.
Here, "zaginięcie" is used in the nominative case as the subject of the sentence.
Zaginięcie kluczy było problemem dla rodziny.
The disappearance of the keys was a problem for the family.
In this sentence, "zaginięciem" is in the instrumental case, accompanying the preposition "z" to signify means or association.