About the Janssen surname
The surname Janssen is associated with a patronymic formation. The surname ending is typical of a Scandinavian patronymic formation generally meaning “son of.”. A patronymic formation of this kind shows how an older personal name could develop into a family name. Different families could independently adopt a surname formed from the same given name.
Pronunciation:
Jan-sèn/ʒɑ̃sɛn/