register_taxonomy('project_cat', array('projects'), array(
    'labels'                => array(
        'name'              => _x( 'Project Categories', 'taxonomy general name' ),
        'singular_name'     => _x( 'Project Category', 'taxonomy singular name' ),
        'search_items'      => __( 'Search Project Categories' ),
        'all_items'         => __( 'All Project Categories' ),
        'parent_item'       => __( 'Parent Project Category' ),
        'parent_item_colon' => __( 'Parent Project Category:' ),
        'edit_item'         => __( 'Edit Project Category' ),
        'update_item'       => __( 'Update Project Category' ),
        'add_new_item'      => __( 'Add New Project Category' ),
        'new_item_name'     => __( 'New Project Category Name' ),
        'menu_name'         => __( 'Categories' ),
    ),
    'hierarchical' => true,
    'show_ui'      => true,
    'show_in_menu' => true,
));