"not thirtieth." There really isn't a precise single-word antonym for it.
Thirtieth.
The correct spelling for 30th is "thirtieth".
The correct term is "thirtieth" when referring to the ordinal number that comes after the twenty-ninth. It is used in contexts such as dates (e.g., "the thirtieth of the month") or to describe a position in a sequence. "30th" is simply a numerical representation of "thirtieth."
The thirtieth sultan of the Ottoman Empire was Mahmud II.
Thirtieth means being one of 30 equal parts. So one thirtieth is 1/30 and 1/30 as a decimal is 0.0333...
Thirtieth.
adjective
Words that rhyme with "thirtieth" include words like "sixtieth," "edith," and "beneath."
The thirtieth week of calendar year 2011 starts on Monday July 25 and ends on Sunday July 31.
winscosin.
thirtieth
Thirtieth.