pi1 Syllabification: (pi)Pronunciation: /pī/Definition of pi noun the sixteenth letter of the Greek alphabet (Π, π), transliterated as ‘p.’. the numerical value of the ratio of the circumference of a circle to its diameter (approximately 3.14159). [from the initial letter of Greek periphereia 'circumference'] (Pi) [followed by Latin genitive] Astronomy the sixteenth star in a constellation:Pi Herculis Chemistry & Physics relating to or denoting an electron or orbital with one unit of angular momentum about an internuclear axis. symbol (π) the numerical value of pi. (Π) osmotic pressure. (Π) mathematical product. Origin:Greekpi in other Oxford dictionaries Definition of pi in the British & World English dictionary
