A hierarchy of important ranks
In biology, a family is a taxonomic rank, or a taxon at that rank. Each family contains one or more genera. The next important rank is that of order. Usually, the name of the family ends with a "idae" for animals, and "aceae" for plants. Sometimes there are also subfamilies and superfamilies. Subfamilies end with "inae" or "oideae".
In Latin, family is "familia". For example, walnuts (genus Juglans) and hickories (genus Carya) both belong to the walnut family (the Juglandaceae).