cursive script; grass script
Refers to the highly cursive style of writing Chinese characters (and by extension Japanese kanji), one of the major calligraphic styles. Often contrasted with 楷書 (regular script) and 行書 (semi-cursive script).
草書は流れるような線が特徴です。
Cursive script is characterized by flowing lines.
He wrote the poem in cursive script.
この書道の作品は草書で書かれています。
This calligraphy work is written in cursive script.
古い掛け軸の草書はなかなか読めない。
It's quite hard to read the cursive script on the old hanging scroll.
行書 is a semi-cursive style partway between 楷書 and 草書, and learners often mix it up with 草書 because both look flowing, though 草書 abbreviates strokes far more.
highly cursive style; grass style
From Chinese 草書／草书 (cǎoshū), literally 'grass writing', referring to the flowing, grass-like appearance of the strokes.