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# Replace search keywords (whole words)

In case you need to replace certain whole words that the user enters to others (like synonyms), then use this custom code.

[What is this, and where do I put this custom code?](/safe-coding-guideline.md)

```php
add_filter( 'asp_query_args', 'asp_replace_search_keywords', 10, 2 );
function asp_replace_search_keywords( $args, $id ) {
  /**
   * Add as many words as you want. On the left side place the
   * word or words separated by comma to replace.
   * To the right side, place the single word to replace it with.
   */
  $replace = array(
    'word1' => 'word2',       // Replace 'word1' with 'word2'
    'word3, word4' => 'word5' // Replace 'word3' and 'word4' with 'word5'
  );

  // ----------------------------------------
  // Do not change anything below this line
  // ----------------------------------------
  foreach ( $replace as $k => $w ) {
    $kr = explode(',', $k);
    foreach ($kr as $krk => &$krv) {
      $krv = trim($krv);
      if ( $krv == '' ) {
        unset($kr[$krk]);
      } else {
        $krv = '/\b' . $krv . '\b/u';
      }
    }
    if ( count($krv) > 0 ) {
      $args['s'] = preg_replace($kr, $w, $args['s']);
    }
  }
  return $args;
}
```

Follow the instructions within the code to add/remove lines to the **$replace** array variable. Each key is a keyword or keywords separated by comma, and each value is the substitue keyword.