[PHJim]

The terms used to describe mando-things are different depending on where you live or who you talk to.
In North America, a mandola is the "mando" equivalent of the viola, just as the mandolin is the mando equivalent of the mandolin and the mando-cello is the equivalent of the violin-cello. There is a mando-bass that corresponds to the string bass, but it is very rare.
An octave mandolin is an instrument an octave lower than the mandolin.
In Europe I've heard people call this instrument an octave mandola or even just a mandola.
There are words like cittern, bouzouki, Irish bouzouki, blarge, octophone, and other terms that apply to mando-things as well, and not everyone uses them the same way.
Toronto luthier Grit Laskin uses the term "Long neck mandolin" to describe his instruments no matter how many courses or how long the neck.