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

World number one Aryna Sabalenka said she still had room for improvement after a second dominant win in the Brisbane International on Thursday.

From Barron's

But Williams, a former world number one now ranked 582, faded in the third set, Linette breaking her serve twice to move into the second round.

From Barron's

World number one and world champion Luke Littler will play in the event for the third year running.

From BBC

Littler's domination has only ever been matched by Taylor and Van Gerwen in their primes, but whereas the former's spell as the undisputed number one lasted two decades, the latter's was much shorter.

From BBC

"Sealing gaps and draught proofing is the number one step because it's so low cost," he said.

From BBC

Related Words

• champion
• winner