1To make something dirty or to soil; also to pollute or contaminate (e.g., the environment).
新しいシャツにコーヒーをこぼして汚してしまった。
I spilled coffee on my new shirt and dirtied it.
工場排水が川を汚していると批判された。
The factory's wastewater was criticized for polluting the river.
手を汚さずに成功するのは難しいこともある。
Sometimes it's difficult to succeed without getting your hands dirty.
2To disgrace or defile (often used as けがす) — to soil someone's reputation or honor.
彼の不正行為が会社の名を汚した。
His misconduct tarnished the company's name.
無実の罪で家族の名を汚されたと感じた。
I felt that my family's name was disgraced by a false accusation.