Definition of "holy war"

A war that is entirely, primarily, or ostensibly religious in motivation; a war over religion.  examples

(computing, Usenet) A long-running and acrimonious debate or flame war over personal preferences in technical matters, such as the choice between little-endian and big-endian representation.  examples

(Utah) The rivalry between the sports teams of Brigham Young University and the University of Utah.  examples