This is the 14491st most frequent German word.
kriminelle
"Kriminelle" means "criminals" in English.
In this sentence, 'kriminelle' is used as an adjective describing 'Handlung' (act), indicating its illegal nature.
Die kriminelle Handlung wurde von der Polizei untersucht.
The criminal act was investigated by the police.
Here, 'Kriminellen' is a noun referring to persons committing crimes, in its plural form and in a nominative case.
Die Kriminellen planten, in das Museum einzubrechen.
The criminals planned to break into the museum.
'Kriminelle', functioning as an adjective here, describes 'Absichten' (intentions), emphasizing their unlawful character.