From svin (“swine”).
svin-
- (colloquial, intensifier) very, super-
- Synonyms: as-, gör-, jätte-, skit-, ur-, vrål-, bauta-, (usually negative) piss-
Deras nya album är svinbra- Their new album is so damn good
Det kändes svindåligt- It felt super bad
Can be put before virtually any adjective or adverb.