unmentionable

American  

[uhn-men-shuh-nuh-buhl] / ʌnˈmɛn ʃə nə bəl /

adjective

1. not mentionable; inappropriate, unfit, or improper for mention, as in polite conversation; unspeakable.

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noun

1. something that is not to be mentioned.

   That subject was classed among the unmentionables.

2. unmentionables,

   1. undergarments.

   2. (formerly) trousers or breeches.

unmentionable British  

/ ʌnˈmɛnʃənəbəl /

adjective

1. 1. unsuitable or forbidden as a topic of conversation

   2. ( as noun )

      the unmentionable

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Other Word Forms

• unmentionableness
  noun
• unmentionably
  adverb

Etymology

Origin of unmentionable

First recorded in 1820–30; un- ¹ + mentionable

Example Sentences

She plans to sweep away the cobwebs and inject warmth and life into a farm mired in portentous dialogue and unmentionable secrets.

From The Wall Street Journal • Dec. 12, 2025

That relationship, once an unmentionable topic, is now on the agenda of the winning party.

From BBC • May 15, 2023

Her continued focus on class, the great American unmentionable, made Ms. Tax a distinct voice.

From New York Times • Oct. 6, 2022

Family friends recalled Irina McCarthy as her mother’s best friend and their own children’s favorite babysitter, who calmly read aloud the definitions of “various unmentionable words” as the kids giggled endlessly.

From Seattle Times • Jul. 12, 2022

All the unmentionable subjects were now on the table because a measure of mutual trust had been recovered.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis