The 16the letter in the Greek alphabet [∏, π] corresponding in general to English p.

希腊字母中第十六字，即 ∏、π，约与英文字母中的 p 相同。

The number (3.14159+) by which the diameter of a circle must be multiplied in order to find the circumference; indicated by the Greek letter pi [π].

【数】圆周率(用以指圆周与直径之比，用 π 表之)。

The ratio itself, 3.1415926+.

圆周率(即3.1415926)。