Mu (Japanese/Korean), Wu (Chinese traditional: 無, simplified: 无 pinyin: wú), and Vô (in Vietnamese) is a word which can be roughly translated as "none" or "without". While typically used as a prefix to imply the absence of something (e.g., 無線 musen for "wireless"), it is more famously used as a response to certain koans and other questions in Zen Buddhism, intending to indicate that the question itself was wrong.
— wikipedia.org.

無

Вах! Какое оружие в устах толерантного ритора!