一いっ洗せん

noun, noun or participle which takes 'suru'

thoroughly wash away; cleanse completely

Used for washing away dirt, stains, or figurative impurities in one sweeping action. Often appears in formal or written contexts.

• 大おお雨あめが街まちのほこりを一いっ洗せんした。

  The heavy rain thoroughly washed away the dust from the town.

• 彼かれは過か去この汚お名めいを一いっ洗せんしようと努ど力りょくした。

  He strove to completely cleanse himself of his past disgrace.