Strong Warrior in Chinese / Japanese...

The first character, 武, is the spirit or essence of a warrior. The second character, 士, means soldier, officer, or official. 武士 is also used appropriately enough to describe a piece of a chess game. 武士 can also be translated as a soldier, cavalier, palace guard, or samurai, and sometimes as a knight. I've occasionally seen this translated as strong man or tough man (gender not necessarily implied).

By far, 武士 is the most common way to write warrior in Chinese characters, Japanese Kanji, and old Korean Hanja.

Note: In Japanese, this is Bushi, as in Bushido.

See Also:  Knight | Army | Marines | Samurai

不動心 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: An unshakable mind and an immovable spirit is the state of fudoshin. It is courage and stability displayed both mentally and physically. Rather than indicating rigidity and inflexibility, fudoshin describes a condition that is not easily upset by internal thoughts or external forces. It is capable of receiving a strong attack while retaining composure and balance. It receives and yields lightly, grounds to the earth, and reflects aggression back to the source.

Other translations of this title include imperturbability, steadfastness, keeping a cool head in an emergency, or keeping one's calm (during a fight).

The first two Kanji alone mean immobility, firmness, fixed, steadfastness, motionless, and idle.

The last Kanji means heart, mind, soul, or essence.

Together, these three Kanji create a title defined as “immovable mind” within the context of Japanese martial arts. However, in Chinese, it would mean “motionless heart,” and in Korean Hanja, “wafting heart” or “floating heart.”