third principle of the Eight Principles of Yong; downward stroke
Technical calligraphy term for the third stroke in the Eight Principles of Yong (永字八法), a classic set of brushstroke fundamentals. Not used in everyday language.
See also: 永字八法
The third of the Eight Principles of Yong is '努', a vertical downward stroke.
untiring effort; persistent hard work
The character 努 is used here as a technical term for a specific brushstroke in calligraphy. The reading ど is a Sino-Japanese on'yomi.