unpronounceable

Difficult or impossible to pronounce correctly.

Not fit to be mentioned.

Not pronounceable; incapable of being pronounced; difficult to pronounce: as, a harsh, unpronounceable word.

Unfit for being pronounced, named, or mentioned; unmentionable as being offensive to chaste ears.

Impossible or difficult to pronounce or articulate.

Something difficult or impossible to pronounce.

impossible or difficult to pronounce correctly

very difficult to pronounce correctly