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

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

Your envy will only feel bigger and thornier if you treat it as an unmentionable topic or an unthinkable reaction.

From Slate • Oct. 17, 2020

And in that day it was even more disturbing than it is now, because the subject was unmentionable and unmentioned.

From "East of Eden" by John Steinbeck