th

ordinal numbers (序數): 除了 1, 2, 3 是不規則的變化；在數字尾巴加上 th (無聲 /θ/) 即可成為序數，字尾是 y 的，去 y 加 ieth。
• 1st (first), 2nd (second), 3rd (third)
• 4th (fourth), 5th (fifth), 6th (sixth), 7th (seventh), 8th (eighth), 9th (ninth), 10th (tenth), 11th (eleventh), 12th (twelfth), 13th (thirteenth), 14th (fourteenth), 15th (fifteenth), ... 20th (twentieth), ...

th:「麻辣拼盛 Spelling」編號#10第1個拼字字群
th:「麻辣字母拼讀卡」（小卡及大卡）第13張第1個字母組合發音

把 t 換成 th 就變成了另一個單字

t		th (無聲 /θ/)
tank	->	thank
tick	->	thick
torn	->	thorn
tug	->	thug