tjuven

In a sentence

• Tjuven smög sig in i huset under natten.

  The thief sneaked into the house during the night.

  Here, "tjuven" refers to an individual who engages in theft; the definite form indicates specificity as this thief is the subject.

• Vi måste vara försiktiga så att tjuven inte tar våra saker.

  We must be careful so that the thief doesn't take our belongings.

  "Tjuven" is used again in the definite form, referring to a hypothetical or specific known individual who might commit theft.

• Polisen letar fortfarande efter tjuven.

  The police are still searching for the thief.

  In this instance, "tjuven" refers to a person the police are searching for due to their act of theft, showing its typical role as a noun denoting a criminal activity.