framework/helpers/BaseInflector.php
public static function pluralize($word)
    {
        if (isset(static::$specials[$word])) {
            return static::$specials[$word];
        }
        foreach (static::$plurals as $rule => $replacement) {
            if (preg_match($rule, $word)) {
                return preg_replace($rule, $replacement, $word);
            }
        }

        return $word;
    }
public static function pluralize($word)
    {
        if (isset(static::$specials[$word])) {
            return static::$specials[$word];
        }
        foreach (static::$plurals as $rule => $replacement) {
            if (preg_match($rule, $word)) {
                return preg_replace($rule, $replacement, $word);
            }
        }

        return $word;
    }
Converts a word to its plural form.
Note that this is for English only!
For example, 'apple' will become 'apples', and 'child' will become 'children'.
@param string $word the word to be pluralized
@return string the pluralized word