twenty-one
A1Neutral
Definition
Meaning
The cardinal number equivalent to the sum of twenty and one; 21.
The age of legal majority in many contexts (e.g., drinking in the US). The name of various games (e.g., blackjack).
Linguistics
Semantic Notes
Primarily functions as a cardinal number or nominal. Hyphenated when used as an adjective before a noun (e.g., twenty-one students). Can be written as 21.
Dialectal Variation
British vs American Usage
Differences
No significant difference in meaning. Hyphenation rule (twenty-one) applies similarly. The age of majority for alcohol consumption is 21 in the US but 18 in the UK, giving the number different cultural weight.
Connotations
In US: strongly associated with legal drinking age and '21st birthday' celebrations. In UK: more neutral as a number, though '21st birthday' is a traditional coming-of-age milestone.
Frequency
High frequency in both dialects due to its fundamental role as a number.
Vocabulary
Collocations
Grammar
Valency Patterns
[number] + noun (twenty-one books)be + twenty-one (He is twenty-one.)at + twenty-one (He left home at twenty-one.)Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “Blackjack (the card game)”
- “Catch-21 (variation of Catch-22)”
- “21-gun salute”
Usage
Context Usage
Business
Used in reports, statistics, and data (e.g., 'The project will take twenty-one days').
Academic
Common in mathematical, historical, and scientific contexts as a quantity.
Everyday
Extremely common for stating age, quantity, time, and in games.
Technical
Used in computing (e.g., port 21 for FTP), sports (e.g., blackjack, basketball scoring), and law (e.g., legal age statutes).
Examples
By Part of Speech
verb
British English
- She managed to twenty-one her opponent in the points race. (rare, context-specific)
American English
- He twenty-oned me at blackjack. (informal, from the game)
adjective
British English
- We have a twenty-one-day cooling-off period.
American English
- She threw a twenty-first-birthday party. (Note: ordinal form used for birthday)
Examples
By CEFR Level
- I am twenty-one years old.
- My book has twenty-one pages.
- She will turn twenty-one next month, which is a big event in America.
- The recipe requires twenty-one grams of sugar.
- After twenty-one years of service, he finally received a promotion.
- The study involved twenty-one participants from diverse backgrounds.
- The statute mandates a minimum sentence of twenty-one years for the offence.
- He strategically held at twenty-one, knowing the dealer was likely to bust.
Learning
Memory Aids
Mnemonic
Think of 'twenty' (two tens) and add 'one' more. It's one more than the 'round' number twenty.
Conceptual Metaphor
COMING OF AGE (especially in US context). COMPLETION (as in 'blackjack', the ideal score).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Remember the hyphen in adjective position: 'twenty-one' not 'twenty one books'.
- In Russian, word order for age is different ('Ему двадцать один год' vs. 'He is twenty-one').
Common Mistakes
- Writing as '21th' instead of '21st'.
- Omitting the hyphen before a noun: 'twenty one people' (incorrect).
- Confusing 'twenty-first' (ordinal) with 'twenty-one' (cardinal).
Practice
Quiz
Which sentence uses 'twenty-one' correctly as an adjective?
FAQ
Frequently Asked Questions
Use a hyphen when it modifies a noun (twenty-one students). No hyphen when it stands alone (The number is twenty one).
The ordinal form is 'twenty-first' (21st).
It is the legal age for purchasing and consuming alcoholic beverages in all US states.
Informally, yes, primarily in the context of the card game blackjack (meaning to score 21). It is not standard in formal writing.