Rename the default WP taxonomy: category

<?php
add_action('init', 'renameCategory');
function renameCategory() {
    global $wp_taxonomies;

    $cat = $wp_taxonomies['category'];
    $cat->label = 'My Categories';
    $cat->labels->singular_name = 'My Categorie';
    $cat->labels->name = $cat->label;
    $cat->labels->menu_name = $cat->label;
}