twenty-one

twenty-one — noun

1. the number that comes after twenty and before twenty-two, written in digits as 2

1.nounA1
Definition

the number that comes after twenty and before twenty-two, written in digits as 21

Example

Mei turned twenty-one last week and celebrated with her family at a restaurant.

The teacher asked the class to count from one to twenty-one out loud.

counting sequence: from X to Y

Synonyms
  • 21

    the Arabic numeral form of the same number

Usage Note

Twenty-one is written with a hyphen between 'twenty' and 'one'. It can be used as a determiner before a plural noun (twenty-one students) or alone as a number.

Common Mistakes

There are twenty one students in the room.
There are twenty-one students in the room.
compound numbers from twenty-one to ninety-nine must include a hyphen.

2. a card game in which each player tries to get card values adding up to 21, or cl

2.nounB1
Definition

a card game in which each player tries to get card values adding up to 21, or close to it, without going over, and to have a higher total than the dealer

Example

Abigail learned to play twenty-one from her grandmother during the summer break.

A group of friends played twenty-one with a worn deck of cards at the party.

collocation: play twenty-one

Common collocations
  • play twenty-one
  • a hand of twenty-one
  • rules of twenty-one
  • table for twenty-one
Synonyms
  • blackjack

    the standard name for the game in casinos, especially in the US

  • 21

    the shortened name for the game, used in casual speech

Usage Note

This card game is also widely called 'blackjack', especially in casinos and in North America. 'Twenty-one' is more common in informal, social settings outside casinos.

Word family

  • twenty-first
    adjectiveA2
  • twenty-first
    nounB1

Synonym discussion

Sense: noun/2

All three terms refer to the same card game. 'Blackjack' is the most common name in casinos and American English, and is the standard term in gambling contexts. 'Twenty-one' (often shortened to '21') is the original English name and is still widely used in informal social settings such as family gatherings or friendly games. 'Pontoon' is mainly used in Britain and some Commonwealth countries for a very similar game with slightly different rules. For learners outside a casino, 'twenty-one' or '21' are the safest, most neutral choices.

blackjack ↗pontoon21

Etymology

Old EnglishEnglish

The number twenty-one is formed by combining 'twenty' (from Old English 'twentig') and 'one' (from Old English 'ān'). The hyphenated spelling follows the standard pattern for English compound numbers from twenty-one to ninety-nine. The card game takes its name directly from the winning score of 21 points, and has been called 'twenty-one' in English since at least the 18th century.

First known use

1611

1611, in the meaning defined at sense 1