The bref double is a French form. It is similar to the sonnet, but has a different rhyme scheme and does not need to be written in iambic pentameter. This form contains three quatrains (four-line stanzas) followed by a final couplet.
It has three rhymes: a, b, and c. Five of the 14 lines are not part of the rhyme scheme. The c rhyme ends each quatrain. The a and b rhymes are found twice each somewhere within the three quatrains and once in the couplet.
Here are some sample rhyme schemes.
abxc abxc xxxc ab
xaxc xbxc xbac ba
xabc xaxc xbxc ab
You can learn more about this form at Robert Lee Brewer's Poetic Asides and Poetry Magnum Opus.
I hope you'll join me this week in writing a bref double. Please share a link to your poem or the poem itself in the comments.