Learn Swedish: Systemet registrerade intrånget, varigenom mannen kunde arresteras. - The system registered the intrusion, whereby the man could be arrested.

Varigenom is a formal relative adverb that translates to 'whereby' or literally 'where-through'. It combines var (where) and igenom (through). Here, it refers back to the entire preceding clause: the specific event of the system registering the intrusion is the means through which the man could be arrested.

Can I use a less formal phrase instead of varigenom?

Yes! In everyday speech or less formal writing, you will more often hear a preposition plus a relative pronoun. Here, you could replace it with genom vilket (through which). You use the neuter vilket because it refers back to a whole clause rather than a specific en or ett noun.

Why does arresteras end with an -s?

This is the s-passive form. After the auxiliary verb kunde (could), the main verb must be in the infinitive. However, since the man is the one being arrested rather than doing the arresting himself, we add the passive -s ending to the infinitive arrestera, making it arresteras.

What is the root of the word intrånget?

The root is the neuter noun ett intrång (an intrusion), which takes the definite suffix -et here. It comes from the prefix in- and the verb att tränga (to press, force, or crowd), painting a literal picture of someone forcing their way in.