framework/helpers/BaseInflector.php
public static function singularize($word)
    {
        $result = array_search($word, static::$specials, true);
        if ($result !== false) {
            return $result;
        }
        foreach (static::$singulars as $rule => $replacement) {
            if (preg_match($rule, $word)) {
                return preg_replace($rule, $replacement, $word);
            }
        }

        return $word;
    }
public static function singularize($word)
    {
        $result = array_search($word, static::$specials, true);
        if ($result !== false) {
            return $result;
        }
        foreach (static::$singulars as $rule => $replacement) {
            if (preg_match($rule, $word)) {
                return preg_replace($rule, $replacement, $word);
            }
        }

        return $word;
    }
Returns the singular of the $word.
@param string $word the english word to singularize
@return string Singular noun.