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.

---

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

---

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

World number one Nelly Korda won her first US Women's Open title, pipping England's Charley Hull to victory by a single shot.

From BBC • Jun. 8, 2026

She is surely on course to break her major duck sometime soon and in California last Sunday it was only the brilliance of a dominant world number one that bettered the British star.

From BBC • Jun. 8, 2026

Gold has become the number one asset in central banks reserves, thanks to a relentless rise in prices and continued buying from emerging market central banks, the head of next generation research says.

From The Wall Street Journal • Jun. 4, 2026

Though Hong Kong has overtaken Switzerland as the number one in cross-border wealth management, rather than enter panic mode, Swiss banks seem unruffled -- feeling it bolsters the case against looming tighter banking regulations.

From Barron's • Jun. 4, 2026

“I gotta go number one real bad,” Matthew said.

From "The Great Santini" by Pat Conroy

Related Words

• champion
• winner