It is said that there is no word in English that rhymes with MONTH, but GRUNTH, an alternate spelling of granth, rhymes perfectly is one of its pronunciations. Other rhymes for that word are millionth, billionth, trillionth and zillionth.
Word Ways: Vol. 34
, Article 6.
Available at: http://digitalcommons.butler.edu/wordways/vol34/iss2/6