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• fifteen
  fifteen

  noun

  a cardinal number, ten plus five.
• Fifteen
  Fifteen

  noun

  history the Jacobite rising of 1715

fifteen

American  

[fif-teen] / ˈfɪfˈtin /

noun

1. a cardinal number, ten plus five.

2. a symbol for this number, as 15 or XV.

3. a set of this many persons or things.

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adjective

1. amounting to 15 in number.

fifteen ¹ British  

/ ˈfɪfˈtiːn /

noun

1. the cardinal number that is the sum of ten and five

2. a numeral, 15, XV, etc, representing this number

3. something represented by, representing, or consisting of 15 units

4. a rugby union football team

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determiner

1. 1. amounting to fifteen

      fifteen jokes

   2. ( as pronoun )

      fifteen of us danced

Fifteen ² British  

/ ˈfɪfˈtiːn /

noun

1. history the Jacobite rising of 1715

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Usage

Spelling tips for fifteen The word fifteen is hard to spell because it doesn’t simply combine the spelling of the base number, five, with the suffix -teen, as is done in other easy-to-remember spellings like fourteen and sixteen.  How to spell fifteen: When five is combined with suffixes, the ve is turned into an f: fifteen (not fiveteen), fifty (not fivety), and fifth (not fiveth). Remember: there’s no v in fifteen.

Etymology

Origin of fifteen

before 900; Middle English, Old English fiftene. See five, -teen

Example Sentences

A reading below 4% generally triggers a sell signal and it’s worth noting that the median market decline, following the 24 sell signals observed in the last fifteen years, is -1%.

From MarketWatch • May 19, 2026

The last mayoral race began shaping up in 2021, when former City Councilmember Joe Buscaino announced he was running about fifteen months before election day.

From Los Angeles Times • Feb. 5, 2026

Even though the planets are five to ten times larger than Earth, their masses are only five to fifteen times greater.

From Science Daily • Jan. 31, 2026

Three years before production began, director Steven Spielberg invited fifteen experts, including the founder of virtual reality Jaron Lanier, to a three-day summit to reflect on which technologies could possibly exist in the 2050s.

From BBC • Jan. 2, 2026

“More of an electrician. It was a hobby that became a vocation once I turned fifteen and the war began.”

From "The Bletchley Riddle" by Ruta Sepetys and Steve Sheinkin