Real Dictionary

faction
countable noun: A faction is an organized group of people within a larger group, which opposes some of the ideas of the larger group and fights for its own ideas.
uncountable noun: Faction is also used to describe argument and disagreement within a group of people.

faction in American English 1
a group of people inside a political party, club, government, etc. working in a common cause against other such groups or against the main body
noun: a group or clique within a larger group, party, government, organization, or the like

faction in American English 2
a kind of fiction based on or incorporating recognizable historical events, real people, etc.
noun: a form of writing or filmmaking that treats real people or events as if they were fictional or uses them as an integral part of a fictional account

faction in British English 1
noun: a group of people forming a minority within a larger body, esp a dissentious group

faction in British English 2
noun: a television programme, film, or literary work comprising a dramatized presentation of actual events