Faction

A Wikipedia faction is a group of users committed to some view of the project. Those who are less committed are said to have a tendency. Thus one can describe a "tendency to eventualism" or a "deletionism faction", and be generally understood without much ambiguity.

Eventually some of these may evolve into a WikiParty - those forming a power network to change the power structure, by either advocacy or democracy or going on strike. Regime change is sometimes possible in wikis by such methods.

Existing factions presently declared or obvious at Wikipedia include:

those advocating deletionism (and their opponents who advocate inclusionism)
those advocating eventualism (and their opponents who advocate immediatism)
- Also can be viewed as Wikilovers vs Encylopediaists
- or Idealists vs Realists.
those advocating factionalism itself - usually called trolls
those advocating antifactionalism usually calling it "unity" or "harmony" or "community"
those advocating subordinating the online service to the eventual delivery of a static version to offline users
those who believe neutral point of view solves all problems
those who believe in hard ban tactics and try to enforce them by reverting "good edits by bad users" (and their opponents who revert the reverts or rescue text hidden or deleted by their efforts)
anti-American Wikipedians (and their opponents who are pro-American)
those advocating Zionism (and their opponents who are anti-Zionist)

Note:

Careful reflection on these terms reveals that certain factions are the same factions under different names.
It is possible to have a tendency to any of these, but you probably don't belong to a faction unless you are willing to subordinate all tendencies to one over-riding tendency. That defines your faction.
It is also possible to belong to opposing tendencies at different times depending on whether people agree with the way you are editing an article.
A faction is sometimes called a clique