function admin_trim_category_description( $terms, $taxonomies ){
if( 'category' != $taxonomies[0] )return $terms;
$whatever_categories = array('category1', 'hidden', 'category2', 'category3');
foreach( $terms as $key => $term)
if(!in_array($terms[$key]->name, $whatever_categories)) $terms[$key]->description = strip_tags(substr( $term->description, 0, 75 ))."...";
else unset($terms[$key]);
return $terms;
}