Refers to a living arrangement where someone rents a room in a home with some meals included. Alicia became a boarder at the Thompsons', so she has a cozy room and breakfast.
Pro Tip 2/3
Homely Atmosphere
Often implies a more personal, home-like setting, not a professional rental space. As a boarder, Peter often joins the family for movie nights.
Pro Tip 3/3
Cultural Nuance
Boarding can be common in places with housing shortages, or for students and workers. She's a boarder while attending the university in London.