This is the 2947th most frequent Swedish word.
fou
"FoU" in Swedish stands for "forskning och utveckling," meaning "research and development" (R&D).
The word 'fou' is used as a borrowed term (from 'crazy' in French) referring colloquially to someone acting erratically or unusually.
Jag såg en fou på gatan.
I saw a madman on the street.
Here, 'fou' is applied in a theatrical sense, characterizing someone who is eccentric or unconventional, often with connotations of genius.
Skådespelaren spelade rollen som en genialisk fou.
The actor played the role of a brilliant madman.
In this sentence, 'fou' is used figuratively to indicate obsessive love or passion for someone or something.