inconfesable - shameful, unmentionable, unspeakable, unconfessableSpanish example: Algunas veces se escribe un diario para confesar lo inconfesable.
English example: Sometimes a diary is written in order to confess the unspeakable.
Source: inconfesable - shameful, unmentionable, unspeakable, unconfessable (https://www.123teachme.com/spanish_feeds/word_of_the_day/2020/11/6)