Is seclusion limited to a man and a woman being alone together in a place far from sight, or does it include any seclusion between them, even if visible to people?

The unlawful seclusion (khalwa) is not limited to a man being alone with a non-mahram woman in a place hidden from view. Rather, it includes any instance of them being alone in a place where they speak privately, even if they are in full view of people, as long as their conversation cannot be overheard. This is because seclusion was prohibited as it leads to adultery (zina). Therefore, anything that fulfills this meaning is considered to be in the same legal category as physical seclusion.