fortieth

American  

[fawr-tee-ith] / ˈfɔr ti ɪθ /

adjective

1. next after the thirty-ninth; being the ordinal number for 40.

2. being one of 40 equal parts.

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noun

1. a fortieth part, especially of one (1/40).

2. the fortieth member of a series.

fortieth British  

/ ˈfɔːtɪɪθ /

adjective

1. 1. being the ordinal number of forty in numbering or counting order, position, time, etc. Often written: 40th

   2. ( as noun )

      he was the fortieth

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noun

1. 1. one of 40 approximately equal parts of something

   2. ( as modifier )

      a fortieth part

2. the fraction equal to one divided by 40 ( 1/ 40 )

Etymology

Origin of fortieth

before 1100; Middle English fourtithe, Old English fēowertigotha. See forty, -eth ²

Example Sentences

It orbits extremely close to its star, at a distance just one fortieth that of Mercury from the Sun.

From Science Daily • Mar. 22, 2026

For the past 900 years, the coronation has been held in Westminster Abbey - William the Conqueror was the first monarch to be crowned there, and Charles will be the fortieth.

From BBC • Sep. 18, 2022

I recently booked a birthday trip to Europe for my fortieth birthday in 2023 and can’t cancel the plans or will lose out on the money.

From Slate • Sep. 12, 2022

"Administrators cite the omicron variant, but one report says omicron case fatality rate is one fortieth of that of the delta variant," Hurley added in the video.

From Fox News • Jan. 22, 2022

The interruption seemed to have hurt Petrosian’s concentration, because he made some mistakes and resigned on the fortieth move.

From "Endgame" by Frank Brady