This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Not fit to be mentioned or discussed; unspeakable: unmentionable words.

n. One that is not to be mentioned.

n. Underwear.

adj. Not mentionable

Incapable of being mentioned; unworthy of or unfit for being mentioned, named, or noticed.

n. a garment worn under other garments

adj. unsuitable or forbidden as a topic of conversation

"However, I am irrationally obsessed with the idea of mosquito bites in unmentionable places."

impermissible   

unmentionably    unmentionables   

indescribable    ineffable   

unimaginable    unrevealed    masticatory    mid-sixth-century    unimagined    putrescible    vulvar    unequalled    Petrarchan    flowerlike