Definition of phyletism in US English:

phyletism

(also philetism)

noun

Orthodox Church
  • An excessive emphasis on the principle of nationalism in the organization of church affairs; a policy which attaches greater importance to ethnic identity than to bonds of faith and worship; (originally) specifically the claim of the Bulgarian Church to jurisdiction over Bulgarian nationals in all parts of the world.

Origin

Late 19th century; earliest use found in The Catholic World. From modern Greek ϕυλετισμός from ancient Greek ϕυλέτης member of a tribe + -ισμός.