noun, plural: families
(1) A taxonomic rank in the classification of organisms between genus and order.
(2) A taxonomic group of one or more genera, especially sharing a common attribute.
(3) A collection of things or entities grouped by their common attributes, e.g. protein family, gene family, etc.
(4) A group of people descended from a common ancestor; a kin; a tribe.
In taxonomy, a family is more precise than orders but less precise than genera. Organisms belonging to the same family would have evolved from the same ancestors and share relatively common characteristics.
Carolus Linnaeus used the word familia in his Philosophia botanica (1751) to denote major groups of plants; trees, herbs, ferns, palms, etc. And in zoology, the family as a rank intermediate between order and genus was introduced by Pierre André Latreille in his Précis des caractères génériques des insectes, disposés dans un ordre naturel (1796).
Word origin: from the term familia was coined by French botanist Pierre Magnol in 1689 where he called families (familiae) the seventy-six groups of plants he recognized.