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

“Even though that would be fun for you, my number one job is to protect you,” she explains to her daughter.

From The Wall Street Journal • Apr. 5, 2026

“The value of the interim housing, number one, is to save lives,” Bass said.

From Los Angeles Times • Apr. 5, 2026

“Many people feel that the insurance industry has let them down, and the number one company that we hear about is State Farm,” she said.

From Los Angeles Times • Apr. 3, 2026

He accepts Rightmove is the "number one portal" but said costs shouldn't be determined by the company.

From BBC • Apr. 1, 2026

He also saw that “On the Come Up” is the number one song on Dat Cloud.

From "On the Come Up" by Angie Thomas

Related Words

• champion
• winner