A virelai nouveau is a fixed verse form built around a double refrain. It opens with two repeated lines, then the poem alternates those lines at the ends of successive stanzas. In the closing stanza, the two refrains return together in reverse order. The pattern gives the poem a circular feel while still allowing each stanza to develop new material.
Example
First light remembers what the dark has kept,
I wake to hear the winter breathing still;
The harbor sleeps beneath a net of mist.
I wake to hear the winter breathing still,
The gulls move over roofs and frozen poles;
First light remembers what the dark has kept.
The harbor sleeps beneath a net of mist,
I wake to hear the winter breathing still,
The dark has kept, and now the day lets go,
First light remembers what the dark has kept.