the GNU version of the Collaborative International Dictionary of English
noun-plural. The breeches; trousers.
The Century Dictionary and Cyclopedia
Trousers or breeches, as an article of dress not to be mentioned in polite circles; inexpressibles.
Word Usage
"Thus euphemisms are used for undergarments, notably those in touch with the intimate parts, or even, as in the case of the word unmentionables, the trousers worn above these."