Project (CPT) → Services Taxonomy

// Register Custom Taxonomy
function tax_services() {

	$labels = array(
		'name'                       => 'Services',
		'singular_name'              => 'Service',
		'menu_name'                  => 'Service',
		'all_items'                  => 'All Items',
		'parent_item'                => 'Parent Item',
		'parent_item_colon'          => 'Parent Item:',
		'new_item_name'              => 'New Service',
		'add_new_item'               => 'Add New Service',
		'edit_item'                  => 'Edit Service',
		'update_item'                => 'Update Service',
		'view_item'                  => 'View Service',
		'separate_items_with_commas' => 'Separate services with commas',
		'add_or_remove_items'        => 'Add or remove services',
		'choose_from_most_used'      => 'Choose from the most used',
		'popular_items'              => 'Popular Services',
		'search_items'               => 'Search Services',
		'not_found'                  => 'Not Found',
		'no_terms'                   => 'No services',
		'items_list'                 => 'Services list',
		'items_list_navigation'      => 'Services list navigation',
	);
	$args = array(
		'labels'                     => $labels,
		'hierarchical'               => false,
		'public'                     => true,
		'show_ui'                    => true,
		'show_admin_column'          => false,
		'show_in_nav_menus'          => false,
		'show_tagcloud'              => false,
	);
	register_taxonomy( 'service', array( 'project' ), $args );

}
add_action( 'init', 'tax_services', 0 );