An electron is an elementary particle with a negative charge.
In older physics literature, 電子 is sometimes written as 陰電子.
Positron, the antimatter counterpart of the electron. 陰電子 emphasizes the negative charge in contrast to 陽電子.
Compound of 陰 (negative, yin) and 電子 (electron), literally 'negative electron'. Coined in early modern physics to distinguish from 陽電子 (positron).