From Longman Dictionary of Contemporary Englishnuclear familyˌnuclear ˈfamily noun [countable] SSFFAMILYa family unit that consists only of a husband, wife, and children → extended family
Examples from the Corpus
nuclear family• Second, the extended family counts for relatively less and the immediate nuclear family for relatively more.• Religion and the nuclear family went hand in hand.• To return from conjecture to fact: the nuclear family left Lewis in 1944 when I was five years old.• The relationship of the nuclear family to wider social forms has troubled the historian for a long time.• I have been anxious to show that the nuclear family may lead not to satisfaction but to frustration and disappointment.• The result of this dramatic change was the nuclear family.• Three also stands for the relations within the nuclear family, and efforts to ascertain where one fits in there. 