Great Great Great Grandparents
Here is a list of the English and Italian names for several generations of direct ancestors. I presented the Italian in the masculine plural, but you can convert the names to the feminine and/or singular pretty easily by substituting the appropriate ending. I nonni becomes il nonno (for grandfather) or la nonna (for grandmother).
The singular form of "great great grandparents" is trisavo or trisava, but it seems to be more common to use the synonymous trisavolo or trisavola when referring to only one grandparent. The plural of trisavolo would be trisavoli. (Thanks to Francesco for pointing out an earlier error).
I'll admit to having concocted the last formation, although I think the construction would be understood by an Italian genealogist. I didn't want my settimavola Maria Simeone (born in 1683 in Villa Santa Lucia) to be left out.
Degree of Relation