For a word that is not actually ‘real,’ boh sure does get a lot of play in everyday speak.
Meaning, ‘I don’t know,’ ‘no idea,’ boh is uttered by all, in a kind of shoulder-shrug, compulsory way. Kind of like, ‘I wouldn’t know’ or ‘I can’t say…’
Not really finding an etymology of the word, I can only assume it’s onomatopoeic (yay for onomatopoeia!)
Qual’è l’indirizzo della festa?
(“What is the address of the party?” – Boh.)
Pensi che lui abbia una fidanzata?
(“Do you think he has a girlfriend?” – Boh.)
Aò bella! Dov’è la mia macchina?
(“Dude, where’s my car?” – Boh.)