A boarder is someone who pays to live in another person's home, usually receiving meals along with a room. In the 1800s and early 1900s, many families took in boarders to earn extra money. A widow might rent out a spare bedroom to a boarder, serving them breakfast and dinner at the family table. Boarders weren't quite family members but weren't exactly guests either: they lived in the household but paid for the privilege.

Today, boarding is less common in regular homes, but the word survives in boarding school, where students live at their school and receive meals. The term also appears in phrases like boarding house, a building where multiple people rent rooms and eat together.

Don't confuse boarder with border, which sounds identical but means an edge or boundary, like the border between two countries. A helpful memory trick: a boarder lives on board, getting room and board.