number one

American  

noun

1. oneself, especially one's own well-being or interests.

   to look out for number one.

2. a person, company, etc., that is first in rank, order, or prestige.

   Our team is number one.

3. urination: used especially by or with reference to children.

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adjective

1. of the highest in quality, status, importance, etc.; first-rate.

   a number one performance.

2. first in rank, order, or prestige.

   the number one book on the bestseller list.

idioms

1. make / do / go number one, to urinate: used especially by or with reference to children.

number one British  

noun

1. the first in a series or sequence

2. an informal phrase for oneself myself

   to look after number one

3. informal the most important person; leader, chief

   he's number one in the organization

4. informal the bestselling pop record in any one week

5. euphemistic the act or an instance of urination

6. a haircut in which the hair is cut very close to the head with an electric shaver

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adjective

1. first in importance, urgency, quality, etc

   number one priority

2. informal (of a pop record) having reached the top of the charts

Etymology

Origin of number one

First recorded in 1830–40

Example Sentences

In at number one, though, is a force who made the £80m Real Madrid coughed up to prise him from Manchester United in 2009 look like pennies.

From BBC • Apr. 21, 2026

In terms of why she caught the world’s attention and ended up selling so darn many books and becoming such an icon, I think number one, of course, is her talent.

From Slate • Apr. 18, 2026

Anthropic’s co-founder has said the number one thing customers ask for is that chatbots be more honest and free of hallucinations.

From The Wall Street Journal • Apr. 17, 2026

“Our number one priority is the safety of the flying public, and that means ensuring airline schedules reflect what the system can safely handle,” FAA Administrator Bryan Bedford said.

From The Wall Street Journal • Apr. 16, 2026

If we had stayed in Iran, I think Reza would have been my number one best friend.

From "Everything Sad Is Untrue" by Daniel Nayeri

Related Words

• champion
• winner