functions.php

<?php

add_action( 'init', 'aahank_register_taxonomies', 0 );
function aahank_register_taxonomies() {

	// Taxonomy: List
	// For Post Type: Bookmark
	register_taxonomy(
		'aahank_list', // Unique name for the taxonomy
		array( 'aahank_bookmark' ), // Attach to post type(s)
		array( // Arguments
			'labels' => array(
				'name'                       => _x( 'Lists', 'taxonomy general name' ),
				'singular_name'              => _x( 'List', 'taxonomy singular name' ),
				'menu_name'                  => __( 'Lists' ),
				'search_items'               => __( 'Search Lists' ),
				'popular_items'              => __( 'Popular Lists' ),
				'all_items'                  => __( 'All Lists' ),
				'parent_item'                => null,
				'parent_item_colon'          => null,
				'edit_item'                  => __( 'Edit List' ),
				'view_item'                  => __( 'View List' ),
				'update_item'                => __( 'Update List' ),
				'add_new_item'               => __( 'Add New List' ),
				'new_item_name'              => __( 'New List Name' ),
				'separate_items_with_commas' => __( 'Separate lists with commas' ),
				'add_or_remove_items'        => __( 'Add or remove lists' ),
				'choose_from_most_used'      => __( 'Choose from the most used lists' ),
				'not_found'                  => __( 'No lists found.' ),
			),
			'public'              => true,
			'show_ui'             => true,
			'show_in_nav_menus'   => false,
			'show_admin_column'   => true,
			'hierarchical'        => false,
			'query_var'           => 'list', // site/?list=entertainment
			'rewrite' => array(
				'slug'              => 'bookmarks/lists',
				'with_front'        => false,
				'hierarchical'      => false,
			),
			'_builtin'            => false,
		)
	);
}

?>