thirteenth

American  

[thur-teenth] / ˈθɜrˈtinθ /

adjective

1. next after the twelfth; being the ordinal number for 13.

2. being one of 13 equal parts.

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noun

thirteenths plural

1. a thirteenth part, especially of one (1/13).

2. the thirteenth member of a series.

thirteenth British  

/ ˈθɜːˈtiːnθ /

adjective

1. (usually prenominal)

   1. coming after the twelfth in numbering or counting order, position, time, etc; being the ordinal number of thirteen: often written 13th

   2. ( as noun )

      Friday the thirteenth

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noun

1. 1. one of 13 equal or nearly equal parts of something

   2. ( as modifier )

      a thirteenth part

2. the fraction equal to one divided by 13 ( 1/ 13 )

3. music

   1. an interval of one octave plus a sixth See also interval

   2. short for thirteenth chord

Other Word Forms

Noun Inflected Forms

• thirteenths
  plural

Etymology

Origin of thirteenth

before 900; thirteen + -th ²; replacing Middle English thrittenthe ( see three, tenth), Old English thryttēotha ( see tithe)

Example Sentences

The 11 other aircraft can be inspected later, but before their thirteenth flight, that is, 25 cycles, with one cycle consisting of a flight, a takeoff, and a landing.

From Barron's • Jun. 23, 2026

The report also found a thirteenth, now-retired officer, from South Yorkshire Police, would have faced misconduct proceedings.

From BBC • Dec. 2, 2025

The authors of the Speculum paper write that this identification was a mistaken one, the result of a misreading, in the thirteenth century, of an account of the giant written in Latin.

From Science Daily • Mar. 25, 2024

The rescuers saw their hopes dashed on the thirteenth day of the operation, when their drilling machine broke down beyond repair.

From Seattle Times • Nov. 28, 2023

The idea that accurate figures could make a fundamental difference started with double-entry bookkeeping in the thirteenth century; it then spread to the sciences, and outwards from both accountancy and science to government.

From "The Invention of Science" by David Wootton