miswriting a word; using the wrong kanji
A set phrase referring to kanji errors where characters are confused due to visual similarity, especially in copying or writing. Often used in discussions of textual criticism or calligraphy. The phrase originates from the confusion between the characters 魯 and 魚, which look alike in certain scripts.
See also: 烏焉魯魚
魯魚の誤り refers to mistaking kanji with similar shapes.