A household is a group of people who live together as a family. In biblical times, a household was much larger than what we might think of as a family today. It included a father, mother or mothers, children, grandparents, servants, concubines (women who lived with a man but had fewer rights than wives), and sojourners (people staying temporarily with the family).
For example, the household of the patriarch Jacob included 66 people. This was not counting the wives of his sons (Genesis 46:26). The household was treated as one unit, and all members shared responsibility for protecting the family's honor. In 2 Samuel 3:27, we see an example of a household seeking revenge to defend their family's honor.
In the Old Testament, all the males in Abraham’s household were circumcised as a sign of the covenant God made with him (Genesis 17:23). In the New Testament era, there are instances where entire households were baptized (Acts 11:14).