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

“I think public safety is the number one priority, or should be, of all elected officials,” he said.

From Los Angeles Times • May 23, 2026

As well as his four major victories, Sinner has won virtually every other important title and spent 72 weeks as world number one.

From BBC • May 23, 2026

Her previous album, The Good Witch, came out in June 2023 and went straight to number one in the UK's Official Album Chart.

From BBC • May 22, 2026

Jacob Fearnley faces Argentina's Juan Manuel Cerundolo with the likely prospect of world number one Jannik Sinner waiting in round two.

From BBC • May 21, 2026

And he gets to help with money—our number one concern these days.

From "South of Somewhere" by Kalena Miller

Related Words

• champion
• winner