thirtieth

American  

[thur-tee-ith] / ˈθɜr ti ɪθ /

adjective

1. next after the twenty-ninth; being the ordinal number for 30.

2. being one of 30 equal parts.

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noun

• thirtieths
  plural

1. a thirtieth part, especially of one (1/30).

2. the thirtieth member of a series.

thirtieth British  

/ ˈθɜːtɪɪθ /

adjective

1. (usually prenominal)

   1. being the ordinal number of thirty in counting order, position, time, etc: often written 30th

   2. ( as noun )

      the thirtieth of the month

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noun

1. 1. one of 30 approximately equal parts of something

   2. ( as modifier )

      a thirtieth part

2. the fraction equal to one divided by 30 ( 1/ 30 )

Other Word Forms

Noun Inflected Forms

• thirtieths
  plural

Etymology

Origin of thirtieth

before 900; thirty + -eth ²; replacing Middle English thrittythe, Old English thrītegtha

Example Sentences

See Examples For:

thirtieth thirtieths

The difference: Your guests won’t have to feign enthusiasm after the thirtieth photo of you “holding up” the Leaning Tower of Pisa.

From The Wall Street Journal ● Dec. 4, 2025

Hermen Hulst and his co-CEO Hideaki Nishino spoke to the BBC as Sony celebrates the thirtieth anniversary of the console being launched.

From BBC ● Dec. 3, 2024

All that we know is that he passed away in the intake room of the jail one day after his thirtieth birthday.

From Slate ● Oct. 25, 2022

Find the thirtieth term of a sequence where the first term is 16 and the common difference is −5.

From Textbooks ● May 6, 2020

We’ve leaked a fake trail to the Ministry: They think you’re not leaving until the thirtieth.

From "Harry Potter and the Deathly Hallows" by J.K. Rowling

Above twenty-nine thirtieths of the profession submitted to the law.

From The History of England, from the Accession of James II — Volume 3 by Thomas Babington Macaulay, Baron Macaulay