eighteenth

American  

[ey-teenth] / ˈeɪˈtinθ /

adjective

1. next after the seventeenth; being the ordinal number for 18.

2. being one of 18 equal parts.

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noun

eighteenths plural

1. an eighteenth part, especially of one (1/18).

2. the eighteenth member of a series.

eighteenth British  

/ ˈeɪˈtiːnθ /

adjective

1. (usually prenominal)

   1. coming after the seventeenth in numbering or counting order, position, time, etc; being the ordinal number of eighteen: often written 18th

   2. ( as noun )

      come on the eighteenth

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noun

1. 1. one of 18 approximately equal parts of something

   2. ( as modifier )

      an eighteenth part

2. the fraction that is equal to one divided by 18 ( 1/ 18 )

Other Word Forms

Noun Inflected Forms

• eighteenths
  plural

Etymology

Origin of eighteenth

before 900; Middle English eightenthe, eightethe, Old English eahtatēotha. See eighteen + -th ²

Example Sentences

Eighteenth century activities included croquet and designing a custom perfume, all accompanied by fashion photography.

From Los Angeles Times • May 4, 2026

The image was taken in the Eighteenth Century Room at Buckingham Palace three days after Elizabeth died.

From Seattle Times • Sep. 24, 2022

The image was taken in the Eighteenth Century Room at Buckingham Palace last week.

From Reuters • Sep. 23, 2022

The room where the picture was taken is the "Eighteenth Century Room" and the photo has a rather painterly quality, with its rich red and gold colours, the King portrayed in half-light and half-shadow.

From BBC • Sep. 23, 2022

The bells were actually tolling in recognition of Nebraska’s ratifying the Eighteenth Amendment.

From "1919 The Year That Changed America" by Martin W. Sandler