Mushin
Vocabulaire

 無心 / 无心 wú xīn, mu shin むしん, Musim 무심
No Mind

• Chin. unintentionally; not in the mood to 

• Bud. Mindless, without thought, will, or purpose; the real immaterial mind free from illusion; unconsciousness, or effortless action; lacking (defiled) thought 

• Jap. means innocent or without knowledge of good and evil. It literally means “without mind.”
  (1) innocence; (2) insentient (i.e. plants, inanimate objects, etc.); (3) {Buddh} (See 有心) free from obstructive thoughts; (4) to hassle someone (for cash, etc.)

無心 is one of the five spirits of the warrior (budo) and is often used as a Japanese martial arts tenet. Under that context, places such as the Budo Dojo define it this way: “No mind, a mind without ego. A mind like a mirror which reflects and dos not judge.” The original term was “mushin no shin,” meaning “mind of no mind.” It is a state of mind without fear, anger, or anxiety. Mushin is often described by the phrase “Mizu no Kokoro,” which means “mind like water.” The phrase is a metaphor describing the pond that clearly reflects its surroundings when calm but whose images are obscured once a pebble is dropped into its waters.

This has a good meaning in conjunction with Chan / Zen Buddhism in Japan. The term is shortened from mushin no shin (無心の心), a Zen expression meaning the mind without mind and is also referred to as the state of "no-mindness". That is, a mind not fixed or occupied by thought or emotion and thus open to everything. It is translated by D.T. Suzuki as "being free from mind-attachment". 

However, out of that context, it means mindlessness or absent-mindedness. To non-Buddhists in China, this is associated with doing something without thinking. In Korean, this usually means indifference.