single pole; single electrode
Technical term in electrical engineering; refers to a single pole or electrode in a circuit or device.
この回路は単極スイッチを使っている。
This circuit uses a single-pole switch.
単極
We measured the characteristics of the single electrode.
magnetic monopole
Compound of 単 (single) and 極 (pole/electrode). The exact historical derivation is uncertain, but the meaning is transparent from the kanji.