houseguest
A person who stays overnight at someone else’s home.
A houseguest is someone who stays overnight or longer at another person's home. When your grandparents visit for Thanksgiving weekend, they're houseguests. When your best friend sleeps over, they're technically a houseguest too, though we usually use that word for visits lasting several nights.
A houseguest is expected to respect someone else's home and routines. You might make your bed, offer to help with dishes, avoid leaving your stuff scattered everywhere, and follow the household rules even if they're different from your own family's. There's an old saying that houseguests, like fish, start to smell after three days, meaning even welcome visitors can wear out their welcome.
From the host's perspective, having houseguests means preparing space for them, providing meals, and making them feel comfortable. It's a balance: you want guests to feel at home, but they also need to remember they are guests. The word captures this special temporary arrangement where someone lives in your space but isn't part of your household. When houseguests and hosts both do their part, visits can become warm memories instead of awkward experiences.