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.
大雨が街のほこりを一洗した。
The heavy rain thoroughly washed away the dust from the town.
彼は過去の汚名を一洗しようと努
He strove to completely cleanse himself of his past disgrace.