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

At the end of the thirtieth day of festivities, with sixty days more of partying to enjoy, Buttercup was genuinely concerned that she might lack the strength to endure.

From "The Princess Bride" by William Goldman

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