Manetho's chronicle divided his Egyptian king-list into thirty-one dynasties. A dynasty was usually but not always a family of rulers; in some cases rulership was passed from one dynasty to another by peaceful means (through marriage or appointment), but other dynasties seized the throne from their predecessors.
Biographical Dictionary of Ancient Egypt by Rosalie and Antony E. David
Ancient Egypt. A Reference Guide. EdwART. 2011.