miswriting a word; using the wrong kanji
A yojijukugo referring to the error of writing a word with the wrong kanji, especially due to visual similarity. Often used in discussions of classical Chinese or Japanese calligraphy and textual criticism.
See also: 魯魚の誤り (ろぎょのあやまり)
魯魚章草 refers to the mistake of confusing kanji with similar shapes.
A more common phrase for the same concept; 魯魚章草 is a compact yojijukugo version used in literary or academic contexts.
Derived from classical Chinese anecdotes about miswriting 魯 (Lu) for 魚 (fish) and 章 (chapter) for 草 (grass) due to their visual similarity. The exact historical origin is uncertain, but the phrase is traditionally used to warn against careless kanji errors.