They all mean "silly, fool". Are they related or just coincidence? In some Italian dialects (e.g. Tuscany) babbo means "dad", in others (e.g. Sicilian) it means "stupid". In Spanish speaking countries, the exception is Peru, where bobo means "heart". Could it be possible that at least Portuguese, Spanish and Sicilian words are related? Probably the Korean word is not related. But then I have a silly () theory: maybe it's a human instinct that /bVbV/ sounds make people think about silliness? In Italian there are similar words too, like babbeo and babbione. Or even babbuino (lit. "baboon"). Or, taking only the b sound: French bête (lit. beast), Japanese baka, Chinese 笨 pronounced bèn /pən/ in Mandarin, but probably with a /b-/ sound in Middle Chinese, and pronounced /baŋ/ in my Wu dialect.