Definition: Nuclear family refers to a family unit consisting of two parents and their socially recognized children, either biological or adopted. The term nuclear family is most often used to describe a married husband and wife living with their children in one household, as opposed to living with other relatives in an extended family. Historically, it was not unusual for households in many societies to consist of larger extended families. After the industrial revolution, there was a greater emphasis on the nuclear family.
The word nuclear comes from nucleus, the center of many things, or the center around which the other parts of an atom are grouped.