A terzanelle (pronounced tur-zuh-nell) is a poetry form which is a combination of the villanelle and the terza rima. It is nineteen lines total, with five triplets and a concluding quatrain. It uses the interlocked rhyme pattern of a terza rima but in the villanelle’s form of five triplets and a quatrain.
Example
This is Lewis Turco's "Terzanelle in Thunderweather"
This is the moment when shadows gather
under the elms, the cornices and eaves.
This is the center of thunderweather.
The birds are quiet among these white leaves
where wind stutters, starts, then moves steadily
under the elms, the cornices, and eaves--
these are our voices speaking guardedly
about the sky, of the sheets of lightning
where wind stutters, starts, then moves steadily
into our lungs, across our lips, tightening
our throats. Our eyes are speaking in the dark
about the sky, of the sheets of lightening
that illuminate moments. In the stark
shades we inhibit, there are no words for
our throats. Our eyes are speaking in the dark
of things we cannot say, cannot ignore.
This is the moment when shadows gather,
shades we inhibit. There are no words, for
this is the center of thunderweather.