Vocabulary set by another hierarchy and combinations
It's a required part of the entity. The name field for a Drupal 7 taxonomy term is defined in the taxonomy's module:


hook_entity_info() invocation to designate name as the label (a human readable field that's required for displaying entity).
hook_field_extra_fields() invocation to define the name field within the taxonomy term for the admin UI.


The Drupal API does expose hook_entity_info_alter() &amp; hook_field_extra_fields_alter(). You can use these function to redefine how you'd like specify your taxonomy term label field.