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 told them two things: Number one, no nuclear; and number two, stop killing protesters,” the president said.

From The Wall Street Journal • Jan. 31, 2026

Number one rule: you have to take care of yourself first.

From Slate • Nov. 13, 2025

"Number one is trying to convince our friends from different countries to look at the Philippines," Uy told AFP in the shadow of the opulent Sta.

From Barron's • Oct. 25, 2025

"For anyone who thinks that there was any question that we could have touched it: Number one, we could not have. And number two, we would not have. And number three, we did not."

From BBC • Mar. 6, 2025

Number one, Uhmma, I say and hold up my pointer finger.

From "A Step from Heaven" by An Na

Related Words

• champion
• winner