n. pl. fam·i·lies 1. a. A fundamental social group in society typically consisting of one or two parents and their children.
b. The children of one of these groups: She raised a large family.
c. A group of persons related by descent or marriage:
My whole family, including my cousins, gets together once a year. See Usage Note at
collective noun.
2. People in the same line of descent; lineage: comes from an old Virginia family.
3. Obsolete All the members of a household living under one roof.
4. A locally independent organized crime unit, as of the Cosa Nostra.
5. a. A group of like things; a class: the family of brass instruments.
b. A group of individuals derived from a common stock: the family of human beings.
6. Biology A taxonomic category of related organisms ranking below an order and above a genus. A family usually consists of several genera.
7. Linguistics A group of languages descended from the same parent language, such as the Indo-European language family.
8. Mathematics A set of functions or surfaces that can be generated by varying the parameters of a general equation.
9. Chemistry a. A group of elements with similar chemical properties.
b. A vertical column in the periodic table of elements.
10. Physics Any of the three generations of elementary fermions.