extract_singler_word.php

<?php

function singular(string $word)
    {
      //"-es" is used for words that end in "-x", "-s", "-z", "-sh", "-ch" in which case you add
      if (substr($word, -2) == "es") {
        if (substr($word, -4) == "sses") { // eg. 'addresses' to 'address'
          return substr($word, 0, -2);
        } elseif (substr($word, -3) == "ses") { // eg. 'databases' to 'database' (necessary!)
          return substr($word, 0, -1);
        } elseif (substr($word, -3) == "ies") { // eg. 'countries' to 'country'
          return substr($word, 0, -3) . "y";
        } elseif (substr($word, -3, 1) == "x") {
          return substr($word, 0, -2);
        } elseif (substr($word, -3, 1) == "s") {
          return substr($word, 0, -2);
        } elseif (substr($word, -3, 1) == "z") {
          return substr($word, 0, -2);
        } elseif (substr($word, -4, 2) == "sh") {
          return substr($word, 0, -2);
        } elseif (substr($word, -4, 2) == "ch") {
          return substr($word, 0, -2);
        } else {
          return rtrim($word, "s");
        }
      } else {
        return rtrim($word, "s");
      }
    }