Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “number one”

number one

noun [U] (THE BEST)   
the most important, best, most noticeable, or most famous person or organization in a particular area of activity: She's still the world number one in tennis. I'm your number one fan.Winners and losersImportant people and describing important peopleFamous peopleWealthy people
(Definition of number one noun (THE BEST) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
Focus on the pronunciation of number one

Definitions of “number one” in other dictionaries

Translations of “number one”

Word of the Day

altruistic

showing a wish to help or bring advantages to others, even if it results in disadvantage for yourself

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More