functions.php

function get_taxonomy_parents($id, $taxonomy, $link = false, $separator = '/', $nicename = false, $visited = array()) {
    $chain = '';
    $parent = &get_term($id, $taxonomy);

    if (is_wp_error($parent)) {
        return $parent;
    }

    if ($nicename)
        $name = $parent -> slug;
else
        $name = $parent -> name;

    if ($parent -> parent && ($parent -> parent != $parent -> term_id) && !in_array($parent -> parent, $visited)) {
        $visited[] = $parent -> parent;
        $chain .= get_taxonomy_parents($parent -> parent, $taxonomy, $link, $separator, $nicename, $visited);

    }

    if ($link) {
        // nothing, can't get this working :(
    } else
        $chain .= $name . $separator;
    return $chain;
}