attenuator
Technical term in electronics and signal processing for a device that reduces signal amplitude without distorting its waveform.
この回路には減衰器が組み込まれている。
An attenuator is built into this circuit.
信号レベルを調整するために減衰器を使う。
Use an attenuator to adjust the signal level.
Compound of 減衰 (attenuation) and 器 (device). The exact historical derivation is uncertain, but the word is a straightforward technical coinage.