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English definition of “number one”

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
(Definition of number one noun (YOURSELF) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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