This is the 298th most frequent Swedish word.
mord
"Mord" in Swedish means "murder" in English.
Here, 'mord' is used as a noun referring to the act of murder in general.
Mord är en allvarlig förbrytelse.
Murder is a serious crime.
In this sentence, 'mord' represents a specific case of murder being discussed.
Polisen utreder ett mysteriskt mord.
The police are investigating a mysterious murder.
This usage shows 'mord' in the definite form 'mordet,' referring to a particular murder event.