This is the 4492nd most frequent Swedish word.
vargen
"The wolf."
Here the word 'vargen' is a noun referring to a specific animal (the wolf), used in its definite singular form, indicating that the wolf is already known or is unique in context.
Vargen ylar i natten.
The wolf howls in the night.
In this sentence, 'vargen' again is the definite form and is used to specify the particular wolf seen in the forest, demonstrating past event narration.
Jag såg vargen i skogen igår.
I saw the wolf in the forest yesterday.
Here, the word 'vargen' is being introduced generically to state facts about wolves in general, using the definite form for emphasis in informative statements.