〜中 means "throughout": 家中 "all over the house," like 一日中 "all day" and 世界中 "all over the world."
Common collocations
- 家中を探す: to search the whole house
- 家中に響く: to echo through the house
- 家中で: as a whole family
Watch out
Read かちゅう, 家中 is a historical word for the retainers of a feudal lord; in modern speech the word is いえじゅう.