pi electron
Technical term in physics and chemistry; refers to an electron in a pi bond or pi molecular orbital.
In the benzene ring, six pi electrons are delocalized.
Standard scientific notation using the Greek letter π.
Kana spelling of π; used when Greek letters are unavailable or in informal contexts.
Compound of パイ (pi, from the Greek letter π) and 電子 (でんし, electron). The term is a direct calque from English 'pi electron'.