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English definition of “pi”

pi

noun uk   /paɪ/ (symbol Π, π) us  
[U] mathematics, science the number (approximately 3.14) used to calculate the size of circlesLetters of alphabetsLettering and alphabetsMathematical symbols [C or U] language the 16th letter of the Greek alphabet
(Definition of pi from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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