Helen,

"CBOMs" is an acrononym for Citterns, Bouzoukis, and Octave Mandolins(Sometimes referred to as Octave Mandolas).

I own one of the latter. Arguably, a tenor guitar could be added to the list as well but the initials don't fit. ;-))

I have a couple of the above plus a tenor guitar.

Actually, you see less of them around these days in session situations. They are good for accompaniment and lovely to hear playing melody in a smaller grouping or a solo setting.
However, they don't seem to "cut across" as well as some of the higher pitched instruments when playing "the tunes".