The number π is a mathematical constant, the ratio of a circle's circumference to its diameter, commonly approximated as 3.14159. It has been represented by the Greek letter "π" since the mid-18th century, though it is also sometimes spelled out as "pi" (/paɪ/).
近义、反义、联想词
近义词
n.
transcendental number, detective, scientist, man of science, letter, letter of the alphabet, alphabetic character