unmentionable

adj [usu attrib 通常作定语] too shocking or embarrassing to be mentioned or spoken about 说不出口的, 不堪提起的（因说出来会令人震惊或难堪）: an unmentionable disease, eg venereal disease 难以明说的疾病（如性病）.

unlined, unlisted, unliterary, unload, unlock, unlooked-for, unloose, unlovable, unloved, unluckily, unlucky, unmade, unman, unmanageable, unmanly, unmanned, unmannerly, unmarried, unmask, unmatched, unmentionables, unmerchantable, unmindful, unmistakable, unmistakably, unmitigated, unmoved, unmoving, unnatural, unnaturally, unnecessarily, unnecessary, unnerve, unnerving, unnoteworthy, unnoticed, unnumbered, UNO, unobjectionable, unobservable,