noun, na-adjective
unaffected and sincere, with fortitude and vigor
A yojijukugo describing a person or attitude that is simple, honest, and strong-willed. Often used as an ideal of character, especially in educational or moral contexts.
彼は質実剛健な人柄で、多くの人から信頼されている。
He has an unaffected, sincere, and vigorous character, and is trusted by many.
この学校は質実剛健を校訓としている。
This school has 'simple and sturdy' as its motto.