one— first
two— second

three— third
four-fourth?
five— fifth
six— sixth

seven— seventh
eight—eighth
nine—ninth
ten— tenth

基数词 : 表示数目的词称为基数词。其形式如下:
(1).从1——10 one,two,three,four,five,six,seven,eight,nine,ten.
(2).从 11——19 eleven,twelve, thirteen, fourteen, fifteen, sixteen, seventeen,eighteen, nineteen.
这里除 eleven, twelve, thirteen, fifteen, eighteen为特殊形式外,fourteen,sixteen,seventeen,nineteen都是由其个位数形式后添加后缀-teen构成。
参考资料基数词_百度百科

