Improve taxonomy term add/edit form in Drupal 7.x

template.php

<?php

/**
 * Implements hook_form_FORM_ID_alter().
 */
function abc_form_taxonomy_form_term_alter(&$form, &$form_state) {
  // Move all fieldsets into vertical-tabs.
  $form['additional_settings'] = array(
    '#type' => 'vertical_tabs',
  );
  foreach ($form as $key => $value) {
    if (
      is_array($form[$key])
      && isset($form[$key]['#type'])
      && ($form[$key]['#type'] === 'fieldset')
    ) {
      $form[$key]['#group'] = 'additional_settings';
    }
  }

  // Hide `Description` field on term add/edit forms.
  $form['description']['#access'] = FALSE;
}