Softness in Chinese / Japanese...

以柔克剛 can be translated as “Softness Overcomes Hardness,” “Flexibility Overcomes Power,” “Flexibility Overcomes Strength,” “Overcoming Powerful Strength with Flexibility,” or “Use Softness to Conquer Strength.”

剛柔館 is the martial arts style Gojukan or Goju-Kan.

The meaning is “hardness [and] softness hall.”

剛 = Hard, firm, or strong.
柔 = Soft, softness, flexible, supple, yielding, gentleness, or pliant.
館 = Hall, building, school room, or an alternate word for a dojo.

沖縄剛柔館 is the martial arts style Okinawan Gojukan or Okinawan Goju-Kan.

The meaning is “Okinawa hardness [and] softness hall.”

沖縄 = Okinawa.
剛 = Hard, firm, or strong.
柔 = Soft, softness, flexible, supple, yielding, gentleness, or pliant.
館 = Hall, building, school room, or an alternate word for a dojo.

柔軟性 is the Chinese, Japanese Kanji, and Korean Hanja word that means “flexibility.”

It can also mean “compatibility,” “pliability,” “softness” and “elasticity.”

See Also:  Flexibility | Cooperation

剛柔 is a term that means hardness and softness or hard and soft.

剛柔 is also the Chinese character origin of the martial arts style known as Cương Nhu.

Cương Nhu or Cuong Nhu was founded by Grandmaster Ngo Dong in 1965 in Hue, Vietnam, and brought to the U.S. in 1971.

剛 means hard, firm, strong, and just.
柔 means soft, flexible, supple, yielding, softness, and/or gentleness.

Until it was romanized in the mid-17th century by Portuguese missionaries with later influence by French missionaries, Vietnamese was exclusively written in Chinese characters. With some research, you can still figure out the original way to write most Vietnamese words and titles in Chinese characters. That is what I did here to figure out that Cuong Nhu would have been 剛柔 if established in ancient Vietnam.

Same characters are used in Japanese for various Goju schools of Okinawan martial arts, though not the same lineage as the Vietnamese style described above.