A houseful is as many people or things as a house will hold — a house stuffed full. You almost always say a houseful of something: a houseful of guests, a houseful of children, a houseful of boxes. It is a friendly, slightly homely word, not a technical one. It does not mean you own the house, and it is not a tidy count; it just paints the picture of “the place is packed.” Though actually, students often mix it with household. A household is the group who live together as a unit (one household, three people). A houseful is an amount: enough to fill the house, often visitors or stuff that is only there for a while. You can have a small household and still, one weekend, a houseful of relatives.