eighteen

American  

[ey-teen] / ˈeɪˈtin /

noun

eighteens plural

1. a cardinal number, ten plus eight.

2. a symbol for this number, as 18 or XVIII.

3. a set of this many persons or things.

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adjective

1. amounting to 18 in number.

eighteen British  

/ ˈeɪˈtiːn /

noun

1. the cardinal number that is the sum of ten and eight and the product of two and nine See also number

2. a numeral, 18, XVIII, etc, representing this number

3. the amount or quantity that is eight more than ten

4. something represented by, representing, or consisting of 18 units

5. (functioning as singular or plural) a team of 18 players in Australian Rules football

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determiner

1. 1. amounting to eighteen

      eighteen weeks

   2. ( as pronoun )

      eighteen of them knew

Other Word Forms

Noun Inflected Forms

• eighteens
  plural

Etymology

Origin of eighteen

before 1000; Middle English ehtetene, Old English eahtatēne; cognate with Old Norse āttjān, German achtzehn. See eight, -teen

Example Sentences

Toeing the government line, Ratcliffe reiterated that tracking emerging technologies has been his highest priority, "right up there with China," since he took office eighteen months ago.

From Barron's • Jun. 30, 2026

On her podcast, he said he once told his brother Harry: “When I am eighteen, I will never talk to you ever again.”

From The Wall Street Journal • Jun. 9, 2026

He travelled eighteen miles but only after ejecting every loose object from the balloon to enable it to launch.

From Salon • Nov. 3, 2024

But it will be a long time before any of this is resolved - it has already taken eighteen months to get to this point, and no court date has been set.

From BBC • Jun. 5, 2024

The windows all roll down at once, and some boys around eighteen or nineteen poke their heads out.

From "Amari and the Night Brothers" by B.B. Alston