outrageous book; absurd book; sensationalist book
A colloquial, often mocking term for a book that makes wild, unscientific, or absurd claims, typically in the realm of pseudoscience, conspiracy theories, or extreme revisionism. The term is strongly associated with the Japanese 'Tondemo-bon' genre critique.
あの出版社はトンデモ本ばかり出している。
That publisher only puts out outrageous books.
彼の説はまるでトンデモ本の内容だ。
His theory sounds like something out of a sensationalist book.
Most common spelling; katakana トンデモ emphasizes the colloquial, mocking tone.
Hiragana variant, less common but still seen.
Compound of トンデモ (colloquial form of とんでもない, 'outrageous, absurd') and 本 (book). The term gained popularity in the 1990s through the work of critics who catalogued pseudoscientific and revisionist books.