a long novel, often in a number of volumes, dealing with a cross section of society, several generations of a family, etc.
Origin:
Fr, river novel
See roman-fleuve in American Heritage Dictionary 4
nounpl.ro·mans-fleuves
A long novel, often in many volumes, chronicling the history of several generations of a family, community, or other group and often presenting an overall view of society during a particular epoch. Also called saga novel.