The Collaborative International Dictionary of English v.0.48:
houseguest \houseguest\, house guest \house guest\n. a guest entertained and staying overnight in one's house for one or more nights. [WordNet 1.5 +PJC]WordNet (r) 3.0 (2006):
houseguest n 1: a guest entertained in your house [syn: house guest, houseguest]