1
- the sixteenth letter of the Greek alphabet (Π, π), transliterated as 'p'希腊字母表中第十六个字母（译写为p） 。
1.1
- the numerical value of the ratio of the circumference of a circle to its diameter (approximately 3.14159)圆周率。
- ORIGIN: from the initial letter of Greek periphereia circumference.
1.2
Pi
followed by Latin genitive Astronomy the sixteenth star in a constellation【天文】π星（星座中第十六颗星） ：Pi Herculis.
武仙座π星。
1.3
- Chemistry & Physics relating to or denoting an electron or orbital with one unit of angular momentum about an internuclear axis【化, 物理】（具有一个核间轴角动量单位的）电子, 轨函数。
词源
Greek.