taxonomy.php

function twenty_slider(){
    register_taxonomy(
        'twenty_slider_category',  //The name of the taxonomy. Name should be in slug form (must not contain capital letters or spaces).
        'twenty_slider',         //post type name
        array(
            'hierarchical'      => true,
            'label'             => 'Twenty Slider Category',  //Display name
            'query_var'         => true,
            'rewrite'           => array(
                'slug'          => 'twenty/slider/category', // This controls the base slug that will display before each term
                'with_front'    => false // Don't display the category base before
                )
            )
    );
    // add another taxonomy
 }
add_action ('init' , 'twenty_slider');