noun
non-government-approved kanji reading
A kanji reading not included in the official Jōyō Kanji list and therefore not taught in Japanese public schools. Often used in discussions of kanji policy and education.
「表外音訓」とは、常用漢字表に載っていない漢字の読み方のことです。
"Hyōgai onkun" refers to kanji readings that are not listed in the Jōyō Kanji table.
この漢字の表外音訓は、教科書では使われていません。
The non-approved reading of this kanji is not used in textbooks.