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English definition of “number one”

number one

noun [U] uk   us  

number one noun [U] (YOURSELF)

(US also numero uno) informal yourself and no one else: Frank is completely selfish - he only cares about number one. I'm going to look out for number one (= take care of myself only).Personal pronouns

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 from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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